[Spaces] Enhancement in create space UI

[sebelga]

In this PR I've added a few enhancements to the manage Space (create) UI.

• Added a placeholder to indicate what the undefined value means

• Added a new form validation to require the solution view to be set (only when creating a new space)

[sebelga]

/ci

[sebelga]

/ci

[elasticmachine]

Pinging @elastic/appex-sharedux (Team:SharedUX)

[SiddharthMantri]

LGTM! Ran locally - i can see the expected change.

[kibana-ci]

💛 Build succeeded, but was flaky

• Buildkite Build
• Commit: 13b83d2

Failed CI Steps

Metrics [docs]

Async chunks

Total size of all lazy-loaded chunks that will be downloaded as the user navigates the app

id	before	after	diff
spaces	184.5KB	185.1KB	+654.0B

History

• 💛 Build #230401 was flaky 400a70f
• 💔 Build #230372 failed f27072b

To update your PR or re-run it, just comment with:
@elasticmachine merge upstream

cc @sebelga

[sebelga]

Thanks for the review @SiddharthMantri !