Terminal accessibility improvements June 2022

[Tyriar]

This captures feedback that was brought up in #149882 (comment)

• Support cell-by-cell navigation to allow links to be keyboard accessible and more fine grained keyboard selection #69795
  • This one will need a lot of changes
• Allow terminal link detection commands to read links from more than just the viewport #150377
• Allow modifying the command when a recent command is run in the terminal #150375
• After completing a word in the terminal, screen reader user cannot edit of review it #150376
• Evaluate terminal find screen reader support #150379
• Support arrow keys and page up/down without modifier when in terminal navigation mode #149882