Mobile: Resolves #10360: Make most plugins default to being desktop-only

[personalizedrefrigerator]

Summary

This pull request makes the manifest platforms entry default to [ "desktop" ] if not given.

This is an alternate solution to the one presented in #10372.

Fixes #10360.

Issues with this solution

• It may require extra maintenance to keep the plugin website aware of which plugins support mobile.
  • The plugin website will either need to depend on @joplin/lib for this or have a copy of the list included in getDefaultPlatforms.ts.
• I only tested a small subset of all plugins for compatibility with mobile — until these plugins are updated to include platforms: ["desktop","mobile"] in their manifests, it won't be possible to install them on mobile.
  • At present, plugins that are determined to be incompatible with the current Joplin client can't be run at all. To allow testing other plugins on mobile (e.g. to suggest that unmaintained plugins be added to the list in getDefaultPlatforms.ts), it could make sense to allow overriding this behavior. This override might apply only to plugins installed using the "Install from file" button.

[personalizedrefrigerator]

Note: Plugins can mark themselves as supporting mobile by setting "platforms" to ["desktop,"mobile"] in their manifest.json.