update packages to fix some audit warnings, update solution to slnx, add vue-tsc so type validation works

[redwyre]

• Add launch.json and tasks.json to run in VSCode
• Migrate sln to slnx - opening in vs2026 updates the sln to a newer version anyway, so might as well migrate to the new slnx standard which is a lot more concise. Rider, VSCode, VS2022, and VS2026 all can understand the format as of around early 2025 so anything reasonably up to date will be fine. The sln file isn't used in building so this doesn't affect anything other than editing.
• Change VRCX-Cef.csproj debugging type to portable so it can work with VSCode, works with everything.
• Added typescript and tsc-vue for type checking. The setup was there it just didn't work, so this makes it work for .js and adds support for .vue files. I started fixing some warnings but moved that to a separate PR.
• Set .npmrc to only allow packages older than 7 days (which is main window of supply chain attacks)
• Updated packages due to vulnerabilities. Very selective update, nothing newer than a week old except where indicated.
  • showdown (markdown renderer) has a moderate vulnerability but since the input is controlled it should be fine, but it's long since abandoned, used by vue-showdown
  • updated tmp and added override so it can't be added as an older version
  • js-cookie was updated in another commit, but I've added an override so it can't be added as an older version
• Updated build-all.ps1‎ to use absolute path when creating symbolic link because it gave me an error
• Fixed deprecated file warnings in generate-third-party-licenses.js‎
• Updated electron dotnet from 9 to 10, to consolidate dotnet versions on 10.0.8
• Added install-linux-deps.sh to install all linux dependencies (.deb, Ubuntu). Used to set up testing environment for now but can be expanded later.

[Natsumi-sama]

• Leave out npm updates as it's easy to add malicious packages to package-lock.json, also we don't want to update Electron due to a Linux bug.
• Why remove? https://github.com/vrcx-team/VRCX/pull/1771/changes#diff-a5de3e5871ffcc383a2294845bd3df25d3eeff6c29ad46e3a396577c413bf357L11
• Why change? https://github.com/vrcx-team/VRCX/pull/1771/changes#diff-ed8b0302426ae825aac304e345368a78d33f1e9022bce605fb79d375cf8e40c0R39

[redwyre]

• Leave out npm updates as it's easy to add malicious packages to package-lock.json, also we don't want to update Electron due to a Linux bug.

Covered in updated description

• Why remove? https://github.com/vrcx-team/VRCX/pull/1771/changes#diff-a5de3e5871ffcc383a2294845bd3df25d3eeff6c29ad46e3a396577c413bf357L11

It is duplicated two lines below

• Why change? https://github.com/vrcx-team/VRCX/pull/1771/changes#diff-ed8b0302426ae825aac304e345368a78d33f1e9022bce605fb79d375cf8e40c0R39

Doesn't work in VSCode, works the same as full