* Plugins: Load plugins by order, aesthetic plugin dependency system
Introduces plugins loading in order of installation, BTCPay itself shows up as a system plugin, and that plugins can define other plugins as dependencies.
* use a proper type for plugin dependencies
* rebase fixes
* message when cannot install
* BTCPay Extensions Part 2
This PR cleans up the extension system a bit in that:
* It renames the test extension to a more uniform name
* Allows yo uto have system extensions, which are extensions but bundled by default with the release (and cannot be removed)
* Adds a tool to help you generate an extension package from a csproj
* Refactors the UI extension points to a view component
* Moves some more interfaces to the Abstractions csproj
* Rename to plugins
* Allow disabling notifications per user and disabling specific notifications per use
closes#1974
* Add disable notifs for all users
* fix term generator for notifications
* sow checkboxes instead of multiselect when js is enabled
* remove js dependency
* fix notif conditions
