Clean up Fork.RI and fix Windows short paths usage

[yannhodiesne]

While investigating around issue #124, I found out a lot of errors were thrown out of the Fork.RI script:

• when using WSL2, uname -a does not contain the WSL build version anymore, making the current check for build 17046 or greater fail with a syntax error because of the format of the regex
• when using Windows short paths to configure Fork's custom git instance (e.g. C:\PROGRA~1 instead of C:\Program Files to avoid spaces), the FORK_RI_EXE_PATH could contain invalid paths as the short name translates PROGRA~1 to Program/ Files, even inside a WSL environment

As such, this PR contains several changes, each one in its own commit:

• a clean up of the Fork.RI script, to follow good practices enforced by the shellcheck tool to avoid syntax errors
• support for WSL2 build version checks, by calling cmd.exe to retrieve the build version consistently (should work with WSL1 too)
• a workaround to enable usage of Windows short paths inside Fork, making it possible to use Fork's interactive rebase tool with setups such as the one described by Interactive Rebase/Commit Squashing not working inside Fork #124

Several downsides can be noted:

• using cmd.exe inside Fork.RI to get WSL build version is slower than using uname
• the Windows short paths workaround could theoretically be avoided if Fork could run the script from a path containing spaces
• I'm not fluent with Rust code, hence the workaround inside the shell script, I don't know if it should stay in Fork.RI or be moved inside fork.rs

As-is, this PR enables the usage of Fork's interactive rebase tool by manually editing %localappdata%/Fork/settings.json to change "GitInstancePath": "C:\\Users\\Surname Lastname\\wslgit\\bin\\git.exe", to "GitInstancePath": "C:\\Users\\SURNAM~1\\wslgit\\bin\\git.exe", (confirmed with the author of #124)

I'm planning on sending a support request to Fork's maintainers to ask them if it could support spaces in Fork.RI's path, enabling wslgit to work under all setups

[andy-5]

Thanks for this PR. I'm not a Fork user myself, so I haven't fully tested it. I added a small comment above, but with that resolved, I think it looks good.

@carlolars What do you think? Could you maybe test/review this PR?

[carlolars]

Hi!

Sorry for my very late response. I've tested this change both with and without a space in the path to Fork and it works for me using WSL2 👍

[yannhodiesne]

Thanks for the reviews, I applied the fix for the sed call to accommodate for build/Build

I also got news from the Fork team, they told me the call to the Fork.RI script is inside of the cross-platform code base, so they are not sure how they should escape spaces properly for now, but they kept it inside their backlog

[andy-5]

Great, I merged your changes into the development branch, so they will be in the next release. Thanks again for your PR.