[Bugfix] Handle dynamically added hx-disable

[Telroshan]

This fixes #1176
When dynamically adding hx-disable to an element from your custom code:

• If any trigger handler is triggered on an element, it first checks if the element is currently disabled or not. If it is, cleans up the element (which removes all htmx listeners from it) & aborts the handler
• You can also call htmx.process right after adding the attribute, to force the clean up immediately

When removing hx-disable from an element from your custom code:

• You will have to explicitly call htmx.process to have htmx initialize that element and bind handlers again

Added test cases for hx-disable dynamic addition / removal

[alexpetros]

These tests are 👍👍