MainMenu UI & Save Game Selection

[EgardA]

PR Checklist

Please check if your PR fulfills the following requirements:

• [ ] All new classes have class-level documentation comments, if there are any at all
• [ ] Tests for the changes have been added (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ X ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] Refactoring (no functional changes, no api changes)
• [ ] Build related changes
• [ ] CI related changes
• [ ] Documentation update
• [ ] Other... Please describe:

What is the current behaviour?

#84

What is the new behaviour?

Resolves #84

Other information

First PR I've ever done, so might have done something wrong..

• ~~Host New Game currently starts the "MP" save as I do not (yet) know how to actually create/launch a new save game~~