Add a `dt run` command with better stdout handling (#8630)
Follow up to https://github.com/flutter/devtools/pull/8621. Polish for https://github.com/flutter/devtools/issues/6486.
The following will be output to the command line after running this command:
```
-------------------------------------------------------------------
The DevTools web app should have just launched on Chrome.
- VM Service URI: http://127.0.0.1:59187/tYhmSvLxKc0=
- DevTools URI for debugging the DevTools web app: http://127.0.0.1:59195?uri=http://127.0.0.1:59187/tYhmSvLxKc0=
The DevTools server is running at: http://127.0.0.1:58976.
- VM Service URI: http://127.0.0.1:58965/mZtiUBxNoBY=/
- DevTools URI for debugging the DevTools server: http://127.0.0.1:58965/mZtiUBxNoBY=/devtools/?uri=ws://127.0.0.1:58965/mZtiUBxNoBY=/ws
-------------------------------------------------------------------
```
