[feat] Git sparse checkout for sourcesdir

[victorusu]

This expands the sourcesdir syntax to include a dictionary format. In this case, the git url is passed via the url key.
Additional command options can be added via the opts key. This capability was previously available in the git_clone function, but not accessible to the sourcesdir git clone interface.

The git sparse-checkout path is available when one defines the files keys with a list of files to checkout.
In this case, instead of emitting a git clone ... command the framework will emit the following set of commands

git clone --no-checkout --depth=1 ...
git sparse-checkout set --no-cone ${file list}
git checkout

where, ${file list} is the list of files defined in the files list.

An example test is this.

@rfm.simple_test
class git_clone_test(rfm.CompileOnlyRegressionTest):
    sourcesdir = {
         'url': 'https://github.com/eth-cscs/alps-gh200-reproducers.git',
         'files' : ['intranode-pinned-host-comm'],
         'opts' : ['--no-optional-locks', '--no-advice', '--no-pager']
    }
    build_system = 'SingleSource'
    sourcepath = 'intranode-pinned-host-comm/intranode_pinned_host_comm.cpp'
    valid_systems = ['*']
    valid_prog_environs = ['*']

Please note that I haven't added any unit tests because the framework does not include any unit tests for the original git_clone function.

closes #3627
closes #3053

[codecov]

Codecov Report

❌ Patch coverage is 29.16667% with 17 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.74%. Comparing base (85b5f6b) to head (a066282).

Files with missing lines	Patch %	Lines
reframe/core/pipeline.py	31.25%	11 Missing ⚠️
reframe/utility/osext.py	25.00%	6 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #3629      +/-   ##
===========================================
- Coverage    91.70%   90.74%   -0.97%     
===========================================
  Files           62       62              
  Lines        13727    13741      +14     
===========================================
- Hits         12589    12469     -120     
- Misses        1138     1272     +134     

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[vkarak]

@victorusu I have updated and rebased your PR. Can you give it a try? I will likely need to add another unit test to increase coverage, but other than that lgtm now.

[vkarak]

Something was messed with the rebase.