Feat get all tags eric

[Thiemann96]

Added simple Route to retrieve all unique tags that are not empty. Used to give suggestions for tags. Results will be cached for 5 minutes.

Description

New GET /getAllTags route which gets all boxes, filters out tags, and response with an array of tags.

Motivation and Context

Used for suggesting new tags to users. Will be implemented in openSenseMapX as autocomplete at registration.

How Has This Been Tested?

Types of changes

• [ ] 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 change)

Checklist:

• [X] My code has been linted using yarn run lint.
• [X] My code does not break the tests (yarn run test)
• [X] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [X] I have read the CONTRIBUTING document.

[mpfeil]

I have converted the PR to a draft pull request. If you are finished just remove the work in progress label and convert it back by clicking Ready for review.