Add german TimeOnly.ToClockNotationConverter

[RenNagasaki]

fixes #1532 Here is a checklist you should tick through before submitting a pull request:

• [x] Implementation is clean
• [x] Code adheres to the existing coding standards; e.g. no curlies for one-line blocks, no redundant empty lines between methods or code blocks, spaces rather than tabs, etc.
• [x] No Code Analysis warnings
• [x] There is proper unit test coverage
• [ ] If the code is copied from StackOverflow (or a blog or OSS) full disclosure is included. That includes required license files and/or file headers explaining where the code came from with proper attribution
• [x] There are very few or no comments (because comments shouldn't be needed if you write clean code)
• [x] Xml documentation is added/updated for the addition/change
• [x] Your PR is (re)based on top of the latest commits from the main branch (more info below)
• [x] Link to the issue(s) you're fixing from your PR description. Use fixes #<the issue number>
• [ ] Readme is updated if you change an existing feature or add a new one
• [x] Run either build.cmd or build.ps1 and ensure there are no test failures

[RenNagasaki]

@dotnet-policy-service agree