Intuitive interface for creating Sync Links for Odoo records

[themreza]

Related to #393

I initially thought about grouping links (mappings) on a per-project basis and used the relation field to store the sync.project ID.
The code for this prototype is available in the first commit.

However, it's more likely that a link is shared across projects and that a single project should be able to link with multiple external systems. The second commit is a prototype without the Record Mappings tab in the Sync Project. It only has the debug menu popup.

[themreza]

I've added the second commit which modifies the prototype so that it is compatible with the current record.set_link method.

extref.mp4

OC_CATEGORY_REL = 'opencart_butopea_category'

def handle_button():
  odoo_website_category = env['product.public.category'].browse(1)
  opencart_category = odoo_website_category.search_links(OC_CATEGORY_REL)

Search links: [('relation', '=', 'opencart_butopea_category'), ('model', '=', 'product.public.category'), ('system1', '=', '__external__'), ('system2', '=', '__odoo__'), ('ref2', 'in', ['1'])] -> sync.link(34,)

[themreza]

I've added these changes in a new module, but if necessary we can embed them into existing source files.

[yelizariev]

@themreza don't hesitate to make the changes directly in sync module. It would be easier to maintain. Thank you for your contribution!

[yelizariev]

v14 is not supported. Target v16 instead.
I close this PR, but the code still might be useful to create the feature in newer versions