Remove `sale` from cooperator dependencies?

[victor-champonnois]

sale does not seem to be needed for the cooperator module. I think we can remove it.

Preliminary tests:

• [x] Removing sale from the dependencies and then installing cooperator doesn't raise any error or warning.
• [x] Testing simple flows works OK
• [x] I did a quick search in the code for stuff that would "seem" to depend on sale but did not find anything.

some observations:

• product is needed but it is already a dependency.
• account journals of type sale are defined in account, not in sale

[robinkeunen]

• [ ] Check that sale remains installed when removed from dependencies.

[victor-champonnois]

closed in favor of https://github.com/OCA/cooperative/issues/16