Refactor Icons

[ElectronicBlueberry]

Remove all string and class icons and replace them with typed IconDefinitions.
Improves tree shaking and should enable us to remove the bundling of all font awesome icons, which we are currently doing.

If icons are used by unused code, this PR removes that code entirely. Also some small refactoring to typescript and composition, where this removes related code complexity.

One remaining question mark is plugins (web-hooks). My current thinking is that we could provide a small per-selected set of icons for web-hooks to use, adding those manually with library.add and documenting which ones are supported.

How to test the changes?

(Select all options that apply)

• I've included appropriate automated tests.
• This is a refactoring of components with existing test coverage.
• Instructions for manual testing are as follows:
  1. [add testing steps and prerequisites here if you didn't write automated tests covering all your changes]

License

• I agree to license these and all my past contributions to the core galaxy codebase under the MIT license.