User configurable plugins manifest URL for Plugin Store

[jjw24]

Provide the option for an user-configurable manifest URL (like an option between github, jsdelivr or user-defined) which will have the following additional benefits:

1. it will be possible to have "unofficial" plugin communities, which means the whole ecosystem is a bit more open
2. it will make it possible to do full integration testing of plugins: for example, before opening a PR to the manifest repository to add a new plugin, I can point my flow-launcher to my fork repository and test that a complete install/update/etc works as expected.

[jjw24]

Might also be a good idea to allow two manifest urls and merge the plugins from both urls into one list. This way user can have plugins from the flow community and others hosted somewhere else.

[github-actions]

This issue is stale because it has been open 45 days with no activity. Remove stale label or comment or this will be closed in 5 days.

[github-actions]

This issue was closed because it has been stale for 7 days with no activity. If you feel this issue still needs attention please feel free to reopen.

[github-actions]

This issue is stale because it has been open 45 days with no activity. Remove stale label or comment or this will be closed in 5 days.

[github-actions]

This issue was closed because it has been stale for 7 days with no activity. If you feel this issue still needs attention please feel free to reopen.