chore: update ready for 1.8.6

[imorland]

Changes proposed in this pull request:

• Uses app.refs.fontawesome to generate the correct fontawesome link
• exports some helpers
• repo maintenance
  requires composer.json core requirement to be bumped before merge

Reviewers should focus on:

Screenshot

Confirmed

• Frontend changes: tested on a local Flarum installation.
• Backend changes: tests are green (run composer test).

Required changes:

• Related Flarum core extension PR's: (Omit this section if irrelevant)