Update Connections form per new design mocks

[noeldevelops]

We now have some design input (after UX review) that should be incorporated into the form. See Figma (internal, screenshot below).
Notes from our review meeting:

• For Test - error state needs improvement to be more visible:
  • Layout of buttons - space between w/results in middle
  • Use Secondary button for Test
  • FieldGroup border color change, messages under an expandable thing, maybe with anchor links?
  • Should we ask the user if they want to search our docs for that error message? https://docs.confluent.io/search.html#stq=Timed+out+waiting+for+a+node+assignment
• Form fields when wrapped remove 50% flex basis
• Fix Radio labels disabled color
• Sidebar: change Warning icon to Error if we can’t connect (FAILED) DONE with set kafkaConfigured and schemaRegistryConfigured to inform direct connection icon+tooltip #903
• Sidebar: Disconnect becomes Remove - change icon to X-ish

Notes from PM @derek1ee :

• Can we make the create/update tab "dirty" when edits have been made (to indicate needing to save/prevent accidental closing). (ON HOLD for doc editing exp)
• SSL, I think usually the word "enable" is not required as that's implied by the checkbox. So maybe just "Use SSL [ ]"
• Field validation - it feels that it's a little too aggressive, e.g. usually even for a required field, it's not colored in error state when it's initially empty, only after it gained focus and then lost, if it's still empty then it will transition to the error state. E.g. today if I switch to basic auth, before I get a chance to enter username/password I get those two text field colored in red immediately.