Resolve "Create new group: Rename form fields and update UI"

What does this MR do?

Introduces the following changes on the "New group" page:

• Rename labels on "New group" page.
  • Group path to Group URL
  • Description to Group description
• Group slug gets generated from Group name.
• Also, let's position the fields similar to the "New project" page.
  • New forms layout (labels on top, bold)
  • Add "(optional) to the Group Description label
  • "Group name" to the top
• Autofocus the 'Group name' input field
• Remove the help icon from the visibility section and replace it with a description + text link.

Screenshots:

before	after

What are the relevant issue numbers?

https://gitlab.com/gitlab-org/gitlab-ce/issues/50962

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• Tests added for this feature/bug
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides

Closes #50962 (closed)