Implement method to process attributes that can be overridden by slots

[luminousleek]

What is the purpose of this pull request?

• [ ] Documentation update
• [ ] Bug fix
• [ ] Feature addition or enhancement
• [x] Code maintenance
• [ ] DevOps
• [ ] Improve developer experience
• [ ] Others, please explain:

Partially resolves #2476

Overview of changes:

Implement processSlotAttribute method and use it for attributes that can be overridden by slots.

Anything you'd like to highlight/discuss:

For reference, these are the attributes that can be overridden by slots:	Component	Attributes
Panel	Header, Alt
Box	Icon, Header
Popover	Header, Content
Modal	Header
Dropdown	Header
Scroll-top-button	Icon
Question	Header, Hint, Answer
Q-Option	Reason
Quiz	Intro
Tooltip	Content
Tab	Header
A-Point	Header, Content, Label

The docs are not correct regarding this.

Testing instructions:

Proposed commit message: (wrap lines at 72 characters)

Implement processSlotAttribute method

There is some duplicated code to process attributes that can
be overridden by slots. In addition, not every attribute that can be
overridden with slots are processed with the 
hasSlotOverridingAttribute method. As such, there will be no
warning in the logger when these attributes are overridden.

Let's put this duplicated code into a method and call it for every
attribute that can be overridden by a slot.

---

Checklist: :ballot_box_with_check:

• [ ] Updated the documentation for feature additions and enhancements
• [ ] Added tests for bug fixes or features (will do in the next PR!)
• [ ] Linked all related issues
• [x] No unrelated changes

---

Reviewer checklist:

Indicate the SEMVER impact of the PR:

• [ ] Major (when you make incompatible API changes)
• [ ] Minor (when you add functionality in a backward compatible manner)
• [x] Patch (when you make backward compatible bug fixes)

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[luminousleek]

The check_docs test is failing because the PR is doing its job - it's giving logger warnings when attributes for a quiz are being overridden:

The warnings arise from the panel in the Header and Hint example with slots at this page (the relevant documentation file is /docs/userGuide/syntax/questions.md), where the code for the question in the panel is

<question type="checkbox" header="Which of the following is true?" hint="Think out of the box! :fas-box:">
  <!-- Header slot -->
  <div slot="header">
<p>Which of the following is correct?</p>
<p>Challenge: Try to get all the answers on your first try! ⭐️ ⭐️</p>
  </div>
<!-- other code omitted for brevity -->
  <!-- Hint slot -->
  <div slot="hint">
<p>Think out of the box! <span aria-hidden="true" class="fas fa-box"></span></p>
<p>Need another hint? <tooltip content="Two of the answers are correct!">Hover over me!</tooltip> <span aria-hidden="true" class="fas fa-mouse-pointer"></span></p>
  </div>
</question>

As can be seen, the header and hint attributes are overridden by their respective slots, which then triggers a logger warning. A simple fix would be to delete the header and hint attributes, so I'm wondering if it's OK to do this in this PR or if I need to create a separate PR for this.

[luminousleek]

I tested the rest of the other attributes for the components to see whether they're able to be overridden by slots.

Looks like the header, content and label attributes for a-point are able to be overridden by slots

Also, the header attribute for tab is also able to be overridden by a slot

As well as the content attribute for tooltip

And the alt attribute for panel

Basically that's all the attributes that are handled by MdAttributeRenderer.ts. The PR is updated to use processSlotAttributes for the rest of the attributes.

[github-actions[bot]]

@kaixin-hc Each PR must have a SEMVER impact label, please remember to label the PR properly.