feat: Add support for acting on workspace comments and icons.

[gonfunko]

In conjunction with RaspberryPiFoundation/blockly#9182, this PR adds support for editing workspace comments, activating their icons via keyboard navigation, and moving them.

[BenHenning]

Generally looks good, though is it possible to add tests for both comment cases?

[gonfunko]

This PR fixes #614.

[gonfunko]

Tests have been added.

[BenHenning]

Thanks @gonfunko. LGTM, though happy to take another pass if you'd like. I did have a few suggestions, but I think they're all hopefully non-controversial.

[BenHenning]

Maybe add a test for toggling to show that it can be expanded.

[gonfunko]

I think that'd be better handled in the core workspace comment tests; my goal here is just to ensure that the keyboard nav infrastructure is hooked up to the underlying views/buttons.

[microbit-matt-hillsdon]

Feedback from @microbit-grace testing workspace comments nav today:

• there's a tab stop for a new workspace comment textarea immediately after creation, is that still intended?
• we think the constrained/unconstrained distinction doesn't make sense for workspace comments so move mode should just do unconstrained without a modifier
• focus styles are particularly unclear (but can fix in MakeCode CSS)

[microbit-matt-hillsdon]

I've used the following styles in MakeCode on our preview branch which includes this PR. Maybe use the same blue as for --blockly-active-tree-color in the plugin if there's enough contrast (MakeCode uses black for that due to a blue top nav bar).

/* Comments are yellow default highlight is orange */
--blockly-active-workspace-comment-color: black;

...

/* Workspace comments */
.blocklyKeyboardNavigation .blocklyComment.blocklyActiveFocus .blocklyCommentHighlight {
    stroke: var(--blockly-active-workspace-comment-color);
    stroke-width: 4px;
}
.blocklyCommentTopbar .blocklyActiveFocus {
    outline: 2px solid var(--blockly-active-workspace-comment-color);
    border-radius: 2px;
    outline-offset: -1px;
}

Yellow on yellow or the orange outline seem too subtle.

[microbit-matt-hillsdon]

Also noticed that comments are not scrolled into view when you navigate to them.

[gonfunko]

Thanks for the feedback! Agreed that all broadly sounds reasonable; I'll merge this as-is to unblock #626 and address those points in a followup later today.