CoreComponents: Add Levels for "headers"

[krewast]

Using the "headers" function of the CoreComponents always creates h1 headers. That's a bit limiting.

This pull request introduces the new attribute "level" for the header function which is used to determine what heading level should be shown. There are officially 6 levels, the default is always h1 (https://developer.mozilla.org/en-US/docs/Web/HTML/Element/Heading_Elements).

Here is how it looks:

And here is the code to check it out yourself:

<.header level="1" class="mt-[1em]">
  Header Level 1 (text-3xl)
</.header>

<.header level="2" class="mt-[1em]">
  Header Level 2 (text-2xl)
</.header>

<.header level="3" class="mt-[1em]">
  Header Level 3 (text-xl)
</.header>

<.header level="4" class="mt-[1em]">
  Header Level 4 (text-lg)
</.header>

<.header level="5" class="mt-[1em]">
  Header Level 5 (text-md)
</.header>

<.header level="6" class="mt-[1em]">
  Header Level 6 (text-sm)
</.header>

At the momemt, running mix test results in serveral warnings that all look like this:

.warning: assign @Level not available in EEx template. Please ensure all assigns are given as options.

It would be great if someone with more Elixir/Phoenix knowledge could have a look at this, because I don't really understand the issue. The attribute "level" has been defined, the type info and default value have been added. Accessing it via "@Level" doesn't differ from accessing @Class, for example. A pointer into the right direction would be helpful, I'm of course willing to add the necessary changes to fix these warnings.

[chrismccord]

Something like this is a nice addition to your own components, but the core components are supposed to be a starting point and learning tool, so I don't think we need to ship this with every app. Thanks!

[krewast]

Alright, I get it, thanks for the feedback.

I just thought it would be cool to have as a default, because creating headings with different levels is such a standard thing to do. And that probably results in many reimplementations of this (or similar) logic where it could be solved once.