Improve support for using VS Code to develop Uyuni

[renner]

What does this PR change?

This patch is to improve the support for using Visual Studio Code to develop Uyuni, especially to work on the Java code using the Java Extension Pack:

• The .project file (used as a template for eclipse setups) is renamed, otherwise VS Code will find it and assumes a java project in that directory.
• The /java/.vscode folder is added to .gitignore.

GUI diff

No difference, only affects development environment setups.

• DONE

Documentation

A wiki page has been created on how to setup VS Code to develop Uyuni:

• https://github.com/uyuni-project/uyuni/wiki/VS-Code-specific-development-instructions

• DONE

Test coverage

No tests needed, only affects development environment setups.

• DONE

Links

No links needed.

• DONE

Changelogs

If you don't need a changelog check, please mark this checkbox:

• No changelog needed

If you uncheck the checkbox after the PR is created, you will need to re-run changelog_test (see below).

Re-run a test

If you need to re-run a test, please mark the related checkbox, it will be unchecked automatically once it has re-run:

• Re-run test "changelog_test"
• Re-run test "backend_unittests_pgsql"
• Re-run test "java_lint_checkstyle"
• Re-run test "java_pgsql_tests"
• Re-run test "schema_migration_test_oracle"
• Re-run test "schema_migration_test_pgsql"
• Re-run test "susemanager_unittests"
• Re-run test "javascript_lint"
• Re-run test "spacecmd_unittests"

[chiaradiamarcelo]

I think @lucidd also uses VS Code for Java

[renner]

I think @lucidd also uses VS Code for Java

Thanks for the hint, I added him as a reviewer.