Add Enter handling to Group create modal

[ZitaNemeckova]

Fixes https://issues.redhat.com/browse/AAH-229

Steps to reproduce:

• login with an account that can create groups
• navigate to the groups page
• hit 'create'
• enter a name for the group - try it with new name as well as a name of an existing group
• hit the key
• observe the page reloading, but your new group doesn't exist/seethere's no create request

Before: The form disappears, the page reloads, but no group is created.
After:

• When filling out the new group form, after filling out a new name of the new group hitting submits the form and the group is created.
• When filling out the new group form, after filling out a name of an existing group hitting you can see that the name input is invalid with error message.

[patchback]

Backport to stable-4.2: 💚 backport PR created

✅ Backport PR branch: patchback/backports/stable-4.2/e576cdd71f7dadad71629c4c2fc5e6c87861f676/pr-355

Backported as #360

🤖 @patchback
I'm built with octomachinery and
my source is open — https://github.com/sanitizers/patchback-github-app.

[patchback]

Backport to stable-4.3: 💚 backport PR created

✅ Backport PR branch: patchback/backports/stable-4.3/e576cdd71f7dadad71629c4c2fc5e6c87861f676/pr-355

Backported as #361

🤖 @patchback
I'm built with octomachinery and
my source is open — https://github.com/sanitizers/patchback-github-app.