* Fixes resulting from audit of issues links
I looked at every link to GitHub in our repo. For cases where we had a TODO that was waiting for a bug to be fixed, and the bug has now been fixed, I applied the pending change. For cases where the link was out of date, I updated the link.
* Update run_test.dart
skip this test again since it failed on linux and macos bots
This uses @kevmoo's completion package to do command line completion for flutter, and a new command "bash-completion" (with alias "zsh-completion") that will output the necessary shell script setup code, and adds the hidden command "completion" that does the actual completion.
Because it adds a dependency, I also had to do flutter update-packages --force-upgrade.
Fixes#18988.
