feat(range): add knobMoveStart and knobMoveEnd events

[amandaejohnston]

Pull request checklist

Please check if your PR fulfills the following requirements:

• Tests for the changes have been added (for bug fixes / features)
• Docs have been reviewed and added / updated if needed (for bug fixes / features)
• Build (npm run build) was run locally and any changes were pushed
• Lint (npm run lint) has passed locally and any fixes were made for failures

Pull request type

Please check the type of change your PR introduces:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation content changes
• Other (please describe):

What is the current behavior?

The only way to listen for user interaction with an ion-range is the ionChange event. This doesn't fit all use cases, as it fires many times throughout a single drag gesture (every time the range's value updates). If a dev wants to listen for the user's gesture to finish, debouncing an ionChange listener wouldn't work either, as it would delay the drag-end handler by the debounce time.

Issue URL: Resolves #17839

What is the new behavior?

Adds two new events: ionKnobMoveStart and ionKnobMoveEnd. These fire at, respectively, the start and end of a touch gesture or mouse drag on the range. Both events include the range's value at the time. Keyboard interaction is also handled.

Does this introduce a breaking change?

• Yes
• No

Other information

[sean-perkins]

I am also indifferent to the event names. I do not think they are immediately recognizable as to what they are used for, but also cannot think of an alternative name that is more clear than ionChangeStart and ionChangeEnd.

[sean-perkins]

Looks good to me, great work on this 🎉

[liamdebeasi]

Do we need to call ensureValueInBounds when emitting the events?

ionic-framework/core/src/components/range/range.tsx

Lines 153 to 155 in a4803ec

	value = this.ensureValueInBounds(value);
	this.ionChange.emit({ value });

I don't know if the valueChanged callback will update the value prop with the clamped values.

[liamdebeasi]

Great job! Don't forget to update the commit subject line to reflect the new event names.

[amandaejohnston]

Good catch, thanks!