Improve accessibility of new LTI admin screen

Follow up for MDL-52154

Problems at the moment

• No feedback when deleting
• If you create a tool proxy but say no to the capabilities it requests, then later go to activate it, the screen reader won't read out the text
• Tab order of type cards wrong: The settings and delete buttons are before the name of the tool
• Feedback screen just says Success for tool proxies
• Feedback screen says close first, should say it last.. Maybe not necessary, we don't do it elsewhere.

Nice to haves

• Automatically focus the new screens that appear to make it easier to use the interface