Added a button to the landing-page and landing-page-event views in the
meetup section. This button, when the nostr attribute contains 'npub1',
links out to the corresponding Nostr page using the nostr attribute value.
This commit adds a calendar stream URL to each meetup. The URL is copied to
the clipboard when the user clicks on a new button added to the UI. The copied
URL can be pasted into a compatible calendar app, allowing the user to easily
add the meetup to their calendar. This feature was added to several views
including 'profile/meetups', 'meetup/landing-page', and
'meetup/landing-page-event'. The associated controller 'DownloadMeetupCalendar'
and livewire components were also updated accordingly.
This commit implements feature flags using the "ylsideas/feature-flags" library and updates various frontend views to show or hide sections based on the feature flag. Additionally, a new migration file is created for the features database table and the LibraryItem model is updated with a new searchLibraryItems function. The composer.json and composer.lock files are updated to include the new dependencies.
