[Canvas] Compress Canvas side panel inputs

[shaunmcgough]

Canvas could benefit from the new EUI compressed layouts being worked on. This would clear up the interface, and make the product fit more into the same space. All around this is some tasty design goodness!

The meta issue for this EUI work is here elastic/eui#2167
Older compressed input styles are here elastic/eui#2174
Form row changes were made here elastic/eui#2181

Several things remain for the EUI project to be complete as of this posting, and we should evaluate this as it unfolds.

[elasticmachine]

Pinging @elastic/kibana-canvas

[ryankeairns]

Closed by #49419