[feat] Include description (descr) in detailed listing

[jack-morrison]

To accommodate a description string, this includes a small adjustment to the details formatting for variant # and file path, putting each on a new line.

Example output:

user@myhost:~/reframe-examples/tutorial$ reframe -C config/baseline_environs.py -c deps/parameterized.py -L
[ReFrame Setup]
  version:           4.9.0-dev.1
  command:           '/usr/local/share/reframe/bin/reframe -C config/baseline_environs.py -c deps/parameterized.py -L'
  launched by:       user@myhost
  working directory: '/home/user/reframe-examples/tutorial'
  settings files:    '<builtin>', 'config/baseline_environs.py'
  selected system:   'tutorialsys'
  check search path: '/home/user/reframe-examples/tutorial/deps/parameterized.py'
  stage directory:   '/home/user/reframe-examples/tutorial/stage'
  output directory:  '/home/user/reframe-examples/tutorial/output'
  log files:         '/tmp/rfm-ajxxgyr9.log'
  results database:  [off] '/home/user/.reframe/reports/results.db'

[List of matched checks]
- TestA %z=0 /7a14ae93
  variant: 0
  file: '/home/user/reframe-examples/tutorial/deps/parameterized.py'
  description: Test A
- TestA %z=1 /8258ae7a
  variant: 1
  file: '/home/user/reframe-examples/tutorial/deps/parameterized.py'
  description: Test A
- TestA %z=2 /423a76e9
  variant: 2
  file: '/home/user/reframe-examples/tutorial/deps/parameterized.py'
  description: Test A
- TestA %z=3 /e62d23e8
  variant: 3
  file: '/home/user/reframe-examples/tutorial/deps/parameterized.py'
  description: Test A
- TestA %z=4 /b1aa0bc1
  variant: 4
  file: '/home/user/reframe-examples/tutorial/deps/parameterized.py'
  description: Test A
- TestA %z=5 /536115e0
  variant: 5
  file: '/home/user/reframe-examples/tutorial/deps/parameterized.py'
  description: Test A
- TestB /cc291487
  variant: 0
  file: '/home/user/reframe-examples/tutorial/deps/parameterized.py'
  description: Test B
    ^TestA %z=9 /ca1c96ee
      variant: 9
      file: '/home/user/reframe-examples/tutorial/deps/parameterized.py'
      description: Test A
    ^TestA %z=8 /75b6718c
      variant: 8
      file: '/home/user/reframe-examples/tutorial/deps/parameterized.py'
      description: Test A
    ^TestA %z=7 /1d87616c
      variant: 7
      file: '/home/user/reframe-examples/tutorial/deps/parameterized.py'
      description: Test A
    ^TestA %z=6 /06c8e673
      variant: 6
      file: '/home/user/reframe-examples/tutorial/deps/parameterized.py'
      description: Test A
Found 11 check(s)

Closes #3458.

[jack-morrison]

I'm having a bit of difficulty getting the new tests to run locally. It's not clear to me what's different about these test classes vs others in the project.

@vkarak, could you please give these a look and point out anything you see me doing incorrectly? Others seem to use the @rfm.simple_test decorator?

== warnings summary ==

unittests/resources/checks/descr_test.py:5
  /usr/local/share/reframe/unittests/resources/checks/descr_test.py:5: PytestCollectionWarning: cannot collect test class 'TestWithDescription' because it has a __init__ constructor (from: unittests/resources/checks/descr_test.py)
    @rfm.simple_test

unittests/resources/checks/descr_test.py:19
  /usr/local/share/reframe/unittests/resources/checks/descr_test.py:19: PytestCollectionWarning: cannot collect test class 'TestWithoutDescription' because it has a __init__ constructor (from: unittests/resources/checks/descr_test.py)
    @rfm.simple_test

unittests/resources/checks/descr_test.py:33
  /usr/local/share/reframe/unittests/resources/checks/descr_test.py:33: PytestCollectionWarning: cannot collect test class 'TestWithEmptyDescription' because it has a __init__ constructor (from: unittests/resources/checks/descr_test.py)
    @rfm.simple_test