docs: add synopsis to list and view commands

Brendan Lynchrequested to merge
8263-list-and-view-synopsis into main

What does this MR do and why?

Adds Long (Synopsis) fields to the shared issuable list and view implementations, as part of the style guide audit identified in #8263. These implementations back both the issue and incident commands.

Commands updated:

  • issue list / incident list
  • issue view / incident view

Content is written generically to work correctly for both issue and incident contexts. It follows the documentation style guide and the GitLab CLI (glab) documentation style guide.

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