[ADD][web_action_conditionable] support forms

[hbrunn]

I added a few other improvements in separate commits, you'll see that in the messages

[tarteo]

@pankk

[tarteo]

<tree create="'some_group' in _group_refs"> in tree views doesn't hide the 'Create' button anymore.

[hbrunn]

@tarteo thanks, didn't consider this use case. Fixed and updated the readme accordingly

[tarteo]

The same case is for trees in form views.

[hbrunn]

I can't reproduce this locally, can you add an example on runbot?

[tarteo]

http://3360805-1205-62dbc4.runbot3.odoo-community.org/web?debug=1#id=3&view_type=form&model=res.groups&action=75

I've changed

<tree string="Access Rules" editable="top">

to

<tree string="Access Rules" editable="top" create="'some_group' in _group_refs">

but I can still add items.

[hbrunn]

aha! you try this in a many2many field, I believe this never has worked: https://github.com/OCA/OCB/blob/8.0/addons/web/static/src/js/view_form.js#L5024

But simple to fix, so I just added that even though not in the scope of this PR.

[tarteo]

The previous worked with one2many and many2many fields on my local machine. But this is more clear. Thanks!

Can you increase the version number in the manifest.

[tbaden]

code review

[OCA-git-bot]

This PR has the approved label and has been created more than 5 days ago. It should therefore be ready to merge by a maintainer (or a PSC member if the concerned addon has no declared maintainer). 🤖

[pedrobaeza]

@hbrunn can you squash commits at your taste?

[hbrunn]

@pedrobaeza done