Add pre-release action

[will-v-pi]

Add a workflow to do pre-releases (using patch version, as VS Code only supports x.x.x versions)

Pre-releases can now be done by dispatching the Pre-release workflow, which will do a patch release and publish the debug version of the extension

Main releases still need to be done as before, and should be limited to major/minor versions to avoid confusion (ie anything that isn't x.x.0 is a pre-release)

[paulober]

Hi @will-v-pi, good idea! Sorry for the late response — I completely missed this during my exam period.

LGTM👍

One small thing I noticed: detecting pre-releases via string matching on "Pre-release" in the commit message is a bit fragile. If the commit message changes slightly or the workflow is triggered by a different event, the logic might behave differently than expected.

In the long run it might be more robust to base this on tags or some explicit signal in the workflow, but for now it should work fine.