Added the ability to change icons of any pinned Board on the Sidebar

[gruen132]

New Feature Submissions:

1. Did you lint your code locally before submission?
   yes
2. Did you test your feature thoroughly to ensure there are no bugs?
   yes
3. Does your feature introduce breaking changes?
   no

Changes to Core Features:

• Have you added an explanation of what your changes do and why you'd like us to include them?
  yes
• Have you written new tests for your core changes, as applicable?
  no
• Have you successfully run tests with your changes locally?
  yes

Please describe your changes

• What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)
  New feature of being able to change the icon of a pinned board in the sidebar by rightclicking on it
• Describe what your code exactly does and if it affects any other part of the code in any way (especially check for breaking changes)
  A seperate menu to change the icon was introduced consisting of a scrollable menu as well as a small search bar for quick searching of specific icons.