[feature request] Add new setting option to ignore checking submodule

[leolcao]

Problem status:

On my windows, the command git submodule status is very slow to cause the opening and refresh in sourcegit also slow.

Request:

For the git repo without submodule, I have a chance to add one setting in the .git/sourcegit.settings or from the GUI preference, to let sourcegit don't run the submodule status command.

Diagnostic messages from git by setting GIT_PERFORMANCE_TRACE=<path/to/log file>

21:26:25.849798 trace.c:416             performance: 0.004758900 s: git command: 'C:\Program Files\Git\mingw64\libexec\git-core\git.exe' submodule--helper status --
21:26:25.858403 trace.c:416             performance: 12.852314500 s: git command: git.exe --no-pager -c core.quotepath=off -c credential.helper=manager -c 'core.editor="D:\LeoCao\Programs\dev-tools\SourceGit\SourceGit.exe" --core-editor' submodule status
21:26:25.948978 trace.c:416             performance: 0.001731100 s: git command: 'C:\Program Files\Git\mingw64\libexec\git-core\git.exe' rev-parse --show-prefix
21:26:26.282106 trace.c:416             performance: 0.001772400 s: git command: 'C:\Program Files\Git\mingw64\libexec\git-core\git.exe' rev-parse --show-toplevel
21:26:27.197954 read-cache.c:2400       performance: 0.003644100 s:  read cache .git/index
21:26:27.199977 trace.c:416             performance: 0.007362500 s: git command: 'C:\Program Files\Git\mingw64\libexec\git-core\git.exe' submodule--helper status --
21:26:27.209085 trace.c:416             performance: 9.466387800 s: git command: git.exe --no-pager -c core.quotepath=off -c credential.helper=manager -c 'core.editor="D:\LeoCao\Programs\dev-tools\SourceGit\SourceGit.exe" --core-editor' submodule status
21:26:35.607092 trace.c:416             performance: 0.000562000 s: git command: git.exe rev-parse --show-toplevel

So, it needs more than 12 and 9 seconds to finish 2 commands: git ... submodule status.

I checked the source code of sourcegit, for now, there is no chance to ignore commands sequence from Repository.cs:

public void RefreshAll()
        {
            Task.Run(() =>
            {
                var allowedSignersFile = new Commands.Config(_fullpath).Get("gpg.ssh.allowedSignersFile");
                _hasAllowedSignersFile = !string.IsNullOrEmpty(allowedSignersFile);
            });

            Task.Run(RefreshBranches);
            Task.Run(RefreshTags);
            Task.Run(RefreshCommits);
            Task.Run(RefreshSubmodules);
            Task.Run(RefreshWorktrees);
            Task.Run(RefreshWorkingCopyChanges);
            Task.Run(RefreshStashes);
        }

For other tool, like vscode, it provides one option git.detectSubmodules, so I can set it to false to avoid submodule detecting.

BTW: I know the root cause of slow performance is not from sourcegit, and I didn't find any useful message from other places to improve the git submodule performance on windows, if someone knows, it will be great and thanks in advance.