feat: support --update-goldens

[trejdych]

hello, I have added support for --update-golden option. It works for --watch mode too, however, I had to filter some files from an observer.

I have added 'g' keyboard shortcut to toggling update goldens mode.

temporary I've pinned riverpod to 2.0.0-dev.3.

Closes #8

PS. It's my first contribution ever so sorry if I did something wrong.

[CLAassistant]

All committers have signed the CLA.

[rrousselGit]

Same here, this needs to be synced with main

[rrousselGit]

It'd be great if you could write a test that uses --update-goldens

[trejdych]

Sure! I'll try to add something.

[rrousselGit]

Awesome. I'll wait for it then. Otherwise your PR looks great, thanks for your work!

[trejdych]

it's my pleasure

[trejdych]

@rrousselGit I've added one test. Let me know if it is enough.

if you don't mind, I would like to add tests for the --watch too (I could do it not only for --update-goldens). However I think it's much more complex topic. Have you thought about it?

[rrousselGit]

It's looking good

Watch mode is a bit tricky indeed. I haven't thought about it too much. I'm open to suggestions

[trejdych]

To be honest I don't have idea yet ;) but I’ll think about it

[rrousselGit]

Sorry for the delay. Thanks for this!