E3-1024: Expand TMPS and SUBS at build time

See merge request e3/e3-require!104

E3-464: Change iocsh PS1 to show IOCNAME

See merge request e3/e3-require!103

Add tests for e3-sequencer compilation

See merge request e3/e3-require!102

This commit also modifies how driver.makefile processes .st/.stt files.
According to the SNL documentation, .stt files should not be pre-processed.
However, driver.makefile has historically been performing the exact same
actions to both types of files, counter to what the documentation said.

Ensure that EPICS_DRIVER_PATH is set first

See merge request e3/e3-require!101

Previously, it was the case that running
```
$ iocsh -r module -l cellMods
$ iocsh -l cellMods -r module
```
would both work correctly, but if you looked at the IOC log it was not
clear why that was the case; in the former case it _appeared_ like we
were finding the module before setting `EPICS_DRIVER_PATH`. This only
worked because this variable is exported from the shell.

This change forces the `-l` flag to be processed _before_ all of the
other flags in order to ensure that paths are determined first.

E3-884: Make non numeric version reinstall prohibited

See merge request e3/e3-require!100

E3-944: Warn if building from install path

See merge request e3/e3-require!99

If a user runs the build from the E3_SITEMODS_PATH, then it can happen that
false dependencies get registered due to how the generated .d files are
parsed to determine module dependencies. Specifically, if you have header
file being used that is located at

${E3_SITEMODS_PATH}/e3-module/module/src/header.h

and it is _not_ being installed, then the dependency parsing script will
see a dependency as an absolute path, and so register that your module
depends on the module `e3-module` version `module`, which is obviously
not what was intended.

While we don't want to stricly _prevent_ a user from building there, it
seems wise to _warn_ a user that there may be unintended consequences.

E3-731: Improve tests

See merge request e3/e3-require!98

Previously, the wrapper fixture would set some environment variables
when running `run_make`; this meant that you could not debug a test
case by simply navigating to the test directory and trying to build
the generated module. This change fixes that.

E3-927: Remove IOCNAME:exit PV from standard E3 iocs

See merge request e3/e3-require!97

As part of E3 there was a decision to remove the IOCNAME:exit.
This pv could lead to unauthorised people to stop and iocs also
is not easy traceble.

In order to do this the BaseVersion PV is now provided by require
and softIocExit.db is no longer loaded.

E3-894: Fix issue where non-existent versions would cause the build to hang

See merge request e3/e3-require!95

The ultimate issue here was that we performed a
```
cat $( ... ) | sed '1d'
```
and if that inner block was empty, then `cat` reverted to waiting for user input. The
error also came up with non-specified build numbers, so we need to make sure that those
are also being fetched correctly.

The upshot is now `<module>_VERSION` will automatically fetch the correct build number;
the only potential downside is that if we have a newer version in `${E3_SITEMODS_PATH}`
in comparison to `${EPICS_MODULES}` (read: cellMods), then it won't pick that up. However,
this seems to be a pretty special corner case.

E3-921: Add test to ensure that failed architectures cause build to fail

See merge request e3/e3-require!94

This adds a test that checks that if a single architecture fails, then the build
fails as a whole.

There are some slight complications in terms of writing good tests, since we do not
want to use real architectures. Since the source files are converted from
`SOURCES -> SRCS -> LIBOBJS` and we finally have the dependency
```make
${DEPFILE}: ${LIBOBJS}
```
we need to ensure that `LIBOBJS` is properly populated before we get to this point.
The challenge, however, is that `LIBOBJS` is defined (in terms of `SRCS` as
```make
LIBOBJS += $(addsuffix $(OBJ),$(notdir $(basename $(filter-out %.$(OBJ) %$(LIB_SUFFIX),$(sort ${SRCS})))))
```
and `LIB_SUFFIX` is set in `${CONFIG}/os/CONFIG.Common.${T_A}`. This is why
we need to do the workaround of hand-defining it at the beginning.

E3-920: Set custom E3_MODULES_PATH for test target

See merge request e3/e3-require!93

The test rule for e3 modules actually does a cellinstall and run the
tests inside this temporary installation. The cellinstall needs to
overwrite some path variables to work this variables were not accessible
through the test rule as they are just changed if cell is on
MAKECMDGOALS. This made impossible to use the standard path variables
inside module's custom test rules.

To fix it the same mechanism used in cellinstall is implemented for test
and the variables paths are now overwritten. This makes possible ie. to
use E3_MODULES_INSTALL_LOCATION_BIN inside custom test rules.

This commit also introduces an unwanted behavior. As the test rule is
now overwriting the standard path variables it cannot longer be along
with the install rule. For example, running `make test install` will
install the module inside the test dir. This is a known issue for
cellinstall as well and a restructure of the Makefile code should be
made to isolate the rules.

E3 924: General require cleanup

See merge request e3/e3-require!92

E3-895: Use bash also for debug on CONFIG_SHELL

See merge request e3/e3-require!91