Better cmdline args specifying server in kuksa-client

[SebastianSchildt]

Will close #657

This tries to simplify connecting to VSS servers using kuksa-client CLI. It uses URIs now, exmaples of valid URIs

grpc://127.0.0.1:55555
grpcs://127.0.0.1:55555
ws://127.0.0.1:8090
wss://127.0.0.1:8090

Other changes

• Changed default (when no command line parameters are given) to connecting to databroker instead of val server
• Removed the "set/getServerAddress" commands within the CLI, instead use `connect
• Updated Readme

When checking this, please also double check whether all variants (TLS/noTLS databroker, val-server) still work.

This is a change in the CLI part only, so the API itself is unaffected

[erikbosch]

I have tested Databroker functionality, works fine. When this is merged we should update https://github.com/eclipse/kuksa.val/wiki/Release-Testing, or at least add a note that it needs to be updated (as part of preparation for next release)

[SebastianSchildt]

Addressed findings. Somebody should still test if TLS and val-server connection works as expected

[lukasmittag]

So basicallay looks better but two inor comments (see below)

[SebastianSchildt]

Comments addressed. I added commits, so it is easier to see what I did. Once this is greenlighted might squash a little bit

[lukasmittag]

LGTM

[erikbosch]

A minor documentation error, but when that is fixed I am happy to have it merged