Sequential version install fix

[nikolai-laevskii]

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

Related issue: https://github.com/actions/setup-dotnet/issues/387

Check list:

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