Generalize facetool strength argument

[db3000]

Take strength for face restoration in the facetool_strength parameter everywhere, instead of gfpgan_strength. This makes usage of non-GFPGAN face restoration much more straightforward, it never made sense to me that I had to pass --ft codeformer --gfpgan_strength 0.5 to run CodeFormer. The change also makes it easier to add more face restoration algorithms and to expose CodeFormer in the web UI.

Mostly just a search and replace, but I left support in for --gfpgan_strength as well on the command line and when loading metadata for backwards compatibility.

[blessedcoolant]

I see the parameter name change but is there any functional change made? Because right now it works exactly like that. the gfpgan_strength is basically a face restoration trigger that works with both gfpgan and codeformer. We just didn't rename it when we added codeformer. The changes seem to be just that. Or am I missing something else here?

If it's just the rename, then I'll test everything works in order and approve it.

[db3000]

If it's just the rename, then I'll test everything works in order and approve it.

It's just the rename for now, which improves clarity in the invoke command line UI. I was thinking to use it to add support for CodeFormer in the web UI in a later PR.

[blessedcoolant]

Okay. Seems good. Please rebase to match the latest changes on dev. Approving this.

@lstein Please do a quick check once before you merge.

[db3000]

Rebased then rebuilt frontend using npm run build.

[lstein]

Looks fine. I'll merge.