Sequential version install fix

[nikolai-laevskii]

⚠️ I recommend merging installer refactoring before processing this PR.

Description

• Added LTS runtime installation before requested dotnet installation:
  When dotnet is installed after usage of some other version, install script fails to override dotnet.exe as it appears to be used by a process. Workaround is to pass --skip-unversioned-files flag to the install script and avoid overriding this file altogether. However, to ensure better compatibility and to avoid vulnerability issues, LTS runtime is now installed first, providing up-to-date unversioned files (such as CLI) for further usage.
• Added E2E tests that check for the problem described in the issue
  • Additional E2E tests were added to address this issue in the future.
  • The new E2E test failing on the main branch with an error as described in the issue: https://github.com/nikolai-laevskii/setup-dotnet/actions/runs/4961107288/jobs/8877470722

Options to consider

1. Running the whole solution on Windows only, as this is the only system where problem appears. This type of change will take minutes to implement, so it's just a matter of preference and how team decides.
2. Reducing number of additional checks down to 3 (one for each platform). 30 additional checks in E2E tests might be excessive, I left them here just for demonstration. Let me know if you want to leave more than 3.
3. Use STS runtime instead of LTS.

Related issue:
actions#387

Check list:

• Mark if documentation changes are required.
• Mark if tests were added or updated to cover the changes.

[nikolai-laevskii]

actions#433