* 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
* BPU Prep Work Part2
* Adjust tests to use the hot wallet when registering deriv scheme
* Add amount to payment data view for onchain payments
* Make zone limits higher when in dev mode (for tests in next PR)
* Make IPaymentMethodDetails serialize/deserialize through payment type using the network
* Allow named settings through settings repo
* Refactor some extensions for next PR
* pr changes
* use json convert for now
* simplify settings changed listening
Might as well use the Event aggregator to listen in on changes instead of the current complicated magic in the settings repo. This also reduces db calls( it sends the new settings through the event instead of fetching them again)
* add settings extension
* switch to old style but using event aggregator
