Improve the way to handle actions

[calixteman]

The pdf in https://bugzilla.mozilla.org/show_bug.cgi?id=1737260 has some buttons where the click action is an array of Hide actions.
So in order to fix that stuff we must make several changes:

1. collect the actions and put them in an array:

• it should be similar to what we have done for _collectJS:

  pdf.js/src/core/core_utils.js

  Line 313 in 3635a9a

  function _collectJS(entry, xref, list, parents) {

2. These actions can be triggered on different kind of events:

• for example for a button it's possible to have Mouse Up, Mouse Down, Mouse Enter, Mouse Exit, On Focus and On Blur events (it's at least what is currently available in Acrobat).
• these events are available for text fields too and probably the others.
• we must respect the array order which means that JS actions must be triggered one by one and with the correct order.

So instead of binding an action on onclick for example we should bind an action which will run the different handlers for the different possible actions (ResetForm, Hide, GoTo, URI, ...).

3. Implement missing actions like Hide.

[freonheat]

I suggest the priority of this issue be increased. There are PDFs out there that work fine in Chrom* and other readers that will not work at all in Firefox, leading to a very bad user experience. See one on #19296