vsix temp package should be mentioned in the PR description

[TwitchBronBron]

When creating a release for vscode-brightscript language (or any project that creates a vsix), the workflow does create a temp vsix under the v0.0.0-releases release. However, it's not linked anywhere in the PR description.

For npm packages we have an install script. For vsix, we should probably show a "click here to download the vsix if you want to test it".

Here's an example action that produced the vsix:
https://github.com/rokucommunity/vscode-brightscript-language/actions/runs/15426845178/job/43415812243?pr=648

You can use this bot's comment as a model. rokucommunity/vscode-brightscript-language#335 (comment)