* cli: added --tls-print-server-cert flag
This prints complete server certificate that is base64 and PEM-encoded.
It is needed for Electron to securely connect to the server outside of
the browser, since there's no way to trust certificate by fingerprint.
* server: added repo/exists API
* server: added ClientOptions to create and connect API
* server: exposed current-user API
* server: API to change description of a repository
* htmlui: refactored connect/create flow
This cleaned up the code a lot and made UX more obvious.
* kopia-ui: simplified repository management UX
Removed repository configuration window which was confusing due to
the notion of 'server'.
Now KopiaUI will automatically launch 'kopia server --ui' for each
config found in the kopia config directory and shut it down every
time repository is disconnected.
See https://youtu.be/P4Ll_LR4UVM for a quick demo.
Fixes#583
