activity-pub-adapter: Wish: Support several account

[rzr]

Currently online one adapter is set, we could setup more (using different accounts) this should be done from the settings page, see gpio-adapter for examples.

Also Sensors could be added to adapter too as we implemented them as webthings too (See example/webthing dir)

Relate-to: https://github.com/rzr/webthing-iotjs/wiki/Social

[rzr]

Also registration from cli could be useful:
https://docs.joinmastodon.org/api/authentication/#example-authorization-code-flow