update docs-link

[miguelcobain]

Migrates the <DocsLink/> component to a glimmer component. This makes it possible to not depend on @ember/legacy-built-in-components.

This also makes this component "officially" public by adding documentation, making it show on the docs site.
Please see inline comments.

[miguelcobain]

You're probably wondering why the hell this is needed.

My first try was

<LinkTo
  @route={{@route}}
  @model={{@model}}
  @models={{@models}}
  @query={{@query}}
  @disabled={{@disabled}}
  @activeClass={{@activeClass}}
  @current-when={{@current-when}}
  ...attributes
  >
  {{yield}}
</LinkTo>

basically proxying every argument that <LinkTo> supports. However, this doesn't work because <LinkTo> is very picky about the arguments we pass to it.

First, we can't pass in @model and @models at the same time, even if one of them is undefined.
Then, even if you just pass @route="something" @model={{undefined}}, the link also won't work. You really need to only pass in @route="something" for those cases.

So, what I'm doing here is basically to understand what arguments were passed to <DocsLink> and then invoking the LinkTo component with only those arguments.

I think this is still worth it since:

• we're only using public apis, so we should be fine
• we're full glimmer components
• we're not relying on @ember/legacy-built-in-components

So, this seems like a more future-proof approach to me.
I think <LinkTo> should validate the arguments values and not just its presence. Basically treating an undefined argument as if it wasn't passed in. That would make the implementation a lot cleaner. But that's a another discussion and maybe a good issue for the ember.js repo.

[miguelcobain]

Passing in an empty hash seems to trick <LinkTo> to behave as if nothing was passed in.
Passing in undefined triggers an error.

[RobbieTheWagner]

This looks good, thanks @miguelcobain! Nice to see we are removing @ember/legacy-built-in-components