Modify call to javac to put options in temp file instead of on command line to prevent problems with command line being too long

[MrPottery]

This branch was created to address the problem of getting 'Command too long' errors from javac becase the classpath is too long.
The change instead writes the javac options to a file in the temporary directory that ALE creates and builds the javac command to use the @<options_file> method of specifying the options.

These changes allowed me to use ALE with my Java projects where previously it failed due to the javac command line being longer than the ~8K allowed by Windows.

[w0rp]

If this is a way forward, and I'll need to think about this idea, we should use the functions in ALE for managing temporary files. Have a look at the documentation for them. I'd link to them, but I'm currently on a train. 😃

[Copilot]

Pull Request Overview

This PR modifies the way javac options are passed to avoid "Command too long" errors by writing options to a temporary file and referencing it via the @file syntax.

• The temporary file now contains the necessary javac options.
• Adjusted path strings for Windows compatibility are applied to classpath and source path options.

[w0rp]

I'll paste this in every open PR: We finally managed to migrate CI checks for Windows from AppVeyor to GitHub Actions, and we've updated the minimum supported Vim version to 8.2. (Thought Vim 8.0 might happen to work for some.) In order to get checks to run again for a PR you'll need to rebase or merge.