WIP Optimize create copy of GitModule()

[gerhardol]

Part of #6357

Separating the second part of #6359 to not mixup discussions
https://github.com/gitextensions/gitextensions/pull/6359/files/07b797b3460c0ceef870f73cab169e9a7cafacdf#diff-a77f67d7f76305a8eeaae638ef09120a

Proposed changes

Make a copy of gitModule instead of creating a new GitModule.
This is the pattern used in similar situations, for instance GitStatusMonitor.

This avoids a call to git rev-parse --common-dir when querying submodules structure/status.
This is not critical in itself, but it is a distraction for #6359.

Note: A previous version (in #6357) used an optimized constructor to create a new instance. This is maybe the pattern that should be used in all similar situations.

Test methodology

• Open refresh a repo with changes in several submodule. For example GE repo with extra files in the submodules
• Verify that there is not a separate call to git-rev-parse for each of the modified repos

✒️ I contribute this code under The Developer Certificate of Origin.

[codecov]

Codecov Report

Merging #6373 into master will decrease coverage by <.01%.
The diff coverage is 51.36%.

@@            Coverage Diff             @@
##           master    #6373      +/-   ##
==========================================
- Coverage   46.84%   46.83%   -0.01%     
==========================================
  Files         688      688              
  Lines       51952    51971      +19     
  Branches     6836     6839       +3     
==========================================
+ Hits        24335    24339       +4     
- Misses      26293    26297       +4     
- Partials     1324     1335      +11

Flag	Coverage Δ
#production	36.32% <49.28%> (+0.03%)	⬆️
#tests	97.49% <100%> (-0.05%)	⬇️

[RussKie]

Make a copy of gitModule instead of creating a new GitModule.
This is the pattern used in similar situations, for instance GitStatusMonitor.

That's actually the only instance of such use I could find through the codebase.
We always construct a new GitModule instance.

[gerhardol]

That's actually the only instance of such use I could find through the codebase.

I found this too in a quick search:

F:\dev\gc\gitextensions_4\GitUI\UserControls\RevisionGrid\RevisionGridControl.cs(749): GitModule capturedModule = Module;

There are at least 20 occurrences in constructors, that is about the same though.

I find about 20 occurrences of new GitModule(path), none to create a thread local module.

For the three (at least) occurrences copying the variable as well as the possibly other occurrences, the creation could be optimized (similar to what I used in the original version):

        public GitModule(GitModule module) : this(module.WorkingDir)
        {
            _gitCommonDirectory = module._gitCommonDirectory;
        }

However, when I test again, I do not see the problem. Will modify the solution some.

[gerhardol]

Pushed an update of the Copy API, as well as avoid creating GitModules for all changed submodules.
The majority of the improvements is from #6389, this primarily removes a distraction.
The second part could be separated (and the API improved).
Set to WIP for now, leave it open for the discussions for #6372.
If not done earlier, this is relevant for remaining parts of #5769

[gerhardol]

Rebased on #6445 (in WIP)
Just two changes remains.
This is not making much difference though (but should maybe be applied in other situations).

[gerhardol]

Will not push this change and likely not other potential changes
(plan to close #5769 without this)