feat: add registering nav items via extension

[JammingBen]

Description

Nav items can be registered with the new extension type SidebarNavExtension, which consists of a AppNavigationItem and optionally scopes (a list of app IDs where the nav item should show).

This PR also adds 2 new optional properties to the AppNavigationItem interface:

• handler - a click handler that get executes on click. It takes priority over a given route.
• priority - a number that determines the nav item's position.

Example extension:

{
  id: 'com.github.owncloud.web.nav.foobar',
  type: 'sidebarNav',
  scopes: ['admin-settings', 'files'],
  navItem: {
    isActive: () => false,
    enabled: () => true,
    name: () => 'Foo Bar',
    icon: 'close',
    handler: () => {
      console.log('some handler')
    },
    priority: 10
  }
}

Related Issue

• Fixes Add Nav-Items to left sidebar #9239

Screenshots (if appropriate):

Types of changes

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

[update-docs]

Thanks for opening this pull request! The maintainers of this repository would appreciate it if you would create a changelog item based on your changes.

[dschmidt]

I'm biased, so another review would be appreciated, but I'm surprisingly cool with this ;-)

[sonarcloud]

SonarCloud Quality Gate failed.   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

22.6% Coverage
0.0% Duplication

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[lookacat]

very nice change 👍🏼

[elizavetaRa]

Very cool!