refactor(ui5-ai-button): change api names

[tsanislavgatev]

We're improving API naming. We have 3 changes in the API.
CHANGE: In the ButtonState we change the splitMode property to showArrowButton.
BEFORE:

<ui5-ai-button-state name="revise" text="Revise" icon="ai" split-mode></ui5-ai-button-state>

NOW:

<ui5-ai-button-state name="revise" text="Revise" icon="ai" show-arrow-button></ui5-ai-button-state>

CHANGE: In the Button, we change the activeArrowButton to arrowButtonPressed following the convention in the framework.

function menuOpenHandler() {
	var button = menu.opener;

	button.activeArrowButton = true;
}

NOW:

function menuOpenHandler() {
	var button = menu.opener;

	button.arrowButtonPressed = true;
}

CHANGE: In the Button we also change the arrow-click event name to arrow-button-click, so the event name is easier to understand and we ensure that it might not be mistaken with the arrow icon when the arrow button is not shown.

myAiButtonSplit.addEventListener("arrow-click", aiButtonSplitArrowClickHandler);

NOW:

myAiButtonSplit.addEventListener("arrow-button-click", aiButtonSplitArrowClickHandler);

[ilhan007]

Let's describe the changes in this manner, but without the breaking change word, maybe just "CHANGE:"

We may decide to describe them and we can just copy/paste the PR description.

[vladitasev]

There was another point of discussion we agreed upon - to follow up with Niki about arrowButtonActive vs arrowButtonPressed - we said, if it's only pressed and nothing else, then "pressed" is the better term, if it has more functionality other than the pressed state, "active" is ok.

[tsanislavgatev]

There was another point of discussion we agreed upon - to follow up with Niki about arrowButtonActive vs arrowButtonPressed - we said, if it's only pressed and nothing else, then "pressed" is the better term, if it has more functionality other than the pressed state, "active" is ok.

It was discussed and it was changed to pressed, but it is wrong in the commit message, as the commit message was written later based on notes from the meeting... Anyways it was agreed to be arrowButtonPressed as it was implemented.

[vladitasev]

Please fix the commit description too (arrowButtonActive is still there in one place)