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

E3-662: Improved IOC startup output

See merge request e3/e3-require!90

E3-453: Remove EPICSVERSION loop

See merge request e3/e3-require!89

This is necessary for the following reason: the previous mechanism used an
eval/call combination that required SUBS and TMPS to be exported on a previous
pass through. This allowed us to use `vpath` for each specific file in order
to locate the correct source files.

In order to avoid that, we add two new ingredients:
* `VPATH` instead of `vpath`, since it allows us to have variables
  that are expanded later
* `.SECONDEXPANSION`, which allows a target (`db_internal`, in this case) to
  perform a second variable expansion at the _end_ of the pass through.

All of this is necessary because the typical module makefile looks like:
```
include driver.makefile

SUBS += ...
```
i.e. `SUBS` and `TMPS` are defined _after_ the inclusion of driver.makefile. If
we don't want to force a re-write of every single module makefile, we needed
to do some of the above changes.

Note that there is something surprising here: `EXCLUDE_ARCHS` _filters_
the architectures (i.e. runs it as %arch%), while `ARCH_FILTER` matches
exactly. This is exactly backwards from what the names suggest.

However, I am leaving this as is for the time being since there are
possibly existing wrappers that use these two variables in this way; a
further investigation should be done to ensure that we can improve this
in some sense. If we make such a change, we should regard it as breaking.

E3-879: driver.Makefile: Add check for inconsistent versions between dependencies

See merge request e3/e3-require!88

In a dependency chain like B->A->C and also B->C where A needs a version
of C different than B the build should fail.
This commit adds this check during dependency treatment on the built
target.

E3-847: Apply all the patches

See merge request e3/e3-require!87

E3-822: Register dependencies for expanded db files

See merge request e3/e3-require!86

This follows the same pattern as the .d files generated during compilation; the
.d files are generated as a side effect of generating the output file, and we
then include them all at build-time to register the correct dependencies. See
line 634 of driver.makefile.

E3-670: Propose linters

See merge request e3/e3-require!85