Support env vars to define filePattern of FileBuildParameterFactory

[gjabouley-invn]

Enable support of environment variables to define filePattern of FileBuildParameterFactory (for every property file, invoke one build)

[gjabouley-invn]

Not sure those checks failures are related to the current change.

Reg. Jenkins builds:

• Test suite hudson.plugins.parameterizedtrigger.test.NodeParametersTest does not timeout on my dev machine.
• Probably subsequent failure is due to above timeout

Reg. Github windows builds:

• Error indicates an infrastructure/VM issue
  jenkins.util.io.CompositeIOException: Unable to delete 'D:\a\parameterized-trigger-plugin\parameterized-trigger-plugin\target\tmp\j h3559511358209244089'. Tried 3 times (of a maximum of 3) waiting 0.1 sec between attempts.

[gjabouley-invn]

After forcing a rebuild, only Github CI windows builds are failing with same errors (cannot delete some files)

[gjabouley-invn]

Can this simple change be merged and included in next plugin release?
Just rebased it on top of latest master

Some tests on Windows build are failing because of a cryptic error, probably not related to this change:
java.io.IOException: Agent failed to connect, even though the launcher didn't report it. See the log output for details.

[gjabouley-invn]

Hi @olamy, i have rebased the change, i think it is ready to merge and provides a reasonably simple but useful enhancement.
Thanks