Add @triggerHtmlTag on <BasicDropdown> and remove @htmlTag option from yielded trigger component (fix glint v2 issue)

[mkszepp]

To achieve full compatibility with template typing (Glint v2), it was necessary to move the @htmlTag property from the Trigger component to the main component, now exposed as @triggerHtmlTag.

If you are using <BasicDropdownTrigger @htmlTag="button">, no changes are required.

However, if you previously used the trigger like this:

<BasicDropdown as |dd|>
  <dd.Trigger @htmlTag="button">Click me!</dd.Trigger>
  <dd.Content>
    Content
  </dd.Content>
</BasicDropdown>

you must update it to:

<BasicDropdown @triggerHtmlTag="button" as |dd|>
  <dd.Trigger>Click me!</dd.Trigger>
  <dd.Content>
    Content
  </dd.Content>
</BasicDropdown>

This issue comes up, while moving to glint v2 (#1032). The typing will be improved in glint v2 branch

Note: Passing @htmlTag directly to the trigger still works at runtime, but it will produce a typing error.