feat: Enable viewing all workflow form sections at once

[SuaYoo]

Resolves #2169

Changes

• Displays workflow form as collapsible sections
• Combines run now toggle into submit
• Fixes exclusion field errors not preventing form submission
• Refactors <btrix-observable> into new Observable controller

Manual testing

1. Log in as crawler
2. Go to New Workflow. Verify scope section is the only section expanded
3. Interact with side navigation and form sections open/close button. Verify sections update as expected
4. Enter invalid fields (like regular expression of **.) Verify form submission is prevent and form is scrolled to the errored field
5. Click "Save". Verify workflow is saved without running
6. Go to New Workflow again
7. Fill required fields and click "Run Crawl". Verify workflow is saved and crawl immediately runs
8. Go to existing workflow. Verify all sections are open and save buttons are always visible
9. Repeat steps 5 and 7 to test saving existing workflow

Screenshots

Page	Image/video
New Workflow
New Workflow
Edit Workflow
Workflow (field errors)

[emma-sg]

Nice, left a few little suggestions! The biggest issue I found here was that the intersection observer currently only made changes when an element went from not visible to visible, which meant that the "Limits" section was never focused at moderate viewport sizes because it starts out already partially visible. The suggestion I made adds a Set of visible panels that gets updated any time panels come in or out of the viewport, and then sets the active panel to the first visible panel instead.

[Shrinks99]

The setup guide link isn't visible when editing, it also seems to be broken (doesn't open the sidebar).

Other than that, looks great! I like the drop shadow for the selection state.

[SuaYoo]

The setup guide link isn't visible when editing, it also seems to be broken (doesn't open the sidebar).

I noticed it's not opening as well, reported in #2335

We never had it enabled in edit, but I'm unsure why, and it makes sense to me to show it in edit as well.

[Shrinks99]

Oop, missed that! Looks good to me then! :)

[tw4l]

Looks great, nice work!