Implement "Create Silence" Feature as a Modal

[bai1024]

1. Modal Implementation : Change the current setting interface to a modal design.
2. Modal Features : Within the modal, Provide input fields to set Silence
3. Support Flexible Silence Setting : Add silence setting field(Matcher), and target field. Matcher field is working like the behavior of Grafana's one

[vincent-olivert-riera]

First review spin done. Nice job :)
Please have a look at my code suggestions and comments.
Thank you very much.

[vincent-olivert-riera]

I have updated everything according to the first review cycle and squashed the commits. Please check.

Second review spin finished.

In some parts I could do GitHub's code suggestion that are easier to commit. In other parts that was not possible due to GitHub limitations.

Please check.

[vincent-olivert-riera]

Looks good to me.

[kfdm]

I think this is somewhat incorrect. We are not always using =~ matches for everything. I think only the instance field is a =~ while others should generally be a regular = match 🤔

[kfdm]

A little buried but

promgen/promgen/prometheus.py

Lines 289 to 296 in 32f1bbd

	kwargs["matchers"] = [
	{
	"name": name,
	"value": value,
	"isEqual": True, # Right now we only support =~
	"isRegex": True if value.endswith("*") else False,
	}
	for name, value in labels.items()

The only time it is a =~ is when our matcher ends with * and in Promgen that is generally only for our quick silence for instance/host