Add stream categories to SearchBar and WidgetQueryControls

[kingzacko1]

Adds a secondary Stream Category filter on the dashboard and widget search bars. Saving searches works, but the search link doesn't currently include stream categories if they exist. Need to work on that part. Otherwise going back to the search page wont repopulate the search correctly without saving the search first.

Plan should be to hide this select behind a feature flag so that it can be used by SecCon, work in queries, but not be visible by default.

/prd Graylog2/graylog-plugin-enterprise#8295 /nocl will be added to changelog on base PR

Description

Motivation and Context

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Refactoring (non-breaking change)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• [ ] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [ ] I have read the CONTRIBUTING document.
• [ ] I have added tests to cover my changes.

[danotorrey]

@kingzacko1 Well done putting this together! It's looking good to me in the frontend and works. I noticed one issue. It seems like when I choose multiple categories and save the search, only the first category appears when the search is loaded. Is that related to the link issue you mentioned?

[kingzacko1]

@danotorrey I've been working through a few minor details in this specific PR to fix that issue and others. Hopefully should have it all wrapped up early next week!