feat(web): subkey-menu fat-finger correction 🐵

[jahorton]

Fixes #4698.

Now that #9778 exists, we have a path forward to finally resolve an old hack:

keyman/web/src/engine/osk/src/visualKeyboard.ts

Lines 578 to 583 in af3ba1f

	// A temp-hack, as this was noted just before 14.0's release.
	// Since a more... comprehensive solution would be way too complex this late in the game,
	// this provides a half-decent stopgap measure.
	//
	// Will not correct to nearby subkeys; only includes the selected subkey and its base keys.
	// Still, better than ignoring them both for whatever base key is beneath the final cursor location.

Subkey fat-finger corrections look simpler to handle / model than multitap corrections, so it seems wise to tackle them first in order to vet the sort of approach (and abstractions) that will be needed for multitaps and flicks down the line.

Furthermore, by fixing this now, we can finally sever the last tie held by VisualKeyboard code to the old-form spec used to distinguish between base key and subkey state. That, in turn, allows us to remove numerous references to old OSK code that is being replaced by the new gesture engine... once we also update the banner to use the gesture engine. Both the removal and the banner patch-up work will be performed in #9752.

@keymanapp-test-bot skip

[keymanapp-test-bot]

User Test Results

Test specification and instructions

User tests are not required

[jahorton]

This obviously is connected to this ongoing Sentry error: https://keyman.sentry.io/share/issue/977c8e43dc1b40ddb7f6948252a6118b/

Note that the new pattern directly uses the object that was previously retrieved by lookup. There will no longer be an inability to find the object.

Of course, that doesn't solve the whole problem - whatever had happened to the layer, and how whatever that is should be handled in relation to fat-fingering - but this should help us get closer to finding the root of the issue, even then.