`-cache` doesn't work with relative path

[williambrode]

Describe the bug:

Running fyne-cross in WSL2 with the -cache option pointing to a windows path didn't fill in the cache.

To Reproduce:

Steps to reproduce the behaviour:

1. In WSL2 install fyne-cross v1.4.0
2. Run fyne-cross linux -cache /c/<path> ...
3. Notice the path will be created but no files will be populated.
4. Doing this with a linux path (like ~/cache) works fine.

Device and debug info (please complete the following information):

Device info

• OS: WSL2 in windows 10
• Go version: 1.22.3
• fyne-cross version: 1.4.0
• Fyne version: 2.4.4

[Jacalz]

This is getting into border-line territory of potentially being a problem with WSL2. If this works for Linux paths but not emulated Windows paths, it looks like maybe the sandbox isn’t working? I’m not sure if even this is something we can do anything about.

Why not run fyne-cross on Windows directly?

[williambrode]

After running into the issue again in CI I think I now understand that the problem was actually that fyne-cross will appear to work with a relative path for -cache when it doesn't. That is to say - it will create the directory, then when it tries to use the directory in docker it won't work because it doesn't pass the absolute path.