[IMP] ORM: Add new --upgrades-paths CLI option

This commit adds a new way to use upgrades scripts folders
whithout needing to symlink them to an hardcoded path.

The folders specified in --upgrades-paths is then being used by
migration.py to find and execute migrations scripts per module
specified in the -u CLI option.

The folder needs to have the following structure:
- <upgrades_paths folder 1>
	- <module1 name>
		- <version1>
			- <script1>
			- <script2>
			- ...
			- <scriptn>
		- <version2>
			- <scripts>
	- <module2 name>
		- <versions>
			- <scripts>
	- ...
- <upgrades_paths folder 2>
	- ...

Update odoo/tools/config.py

Co-Authored-By: Olivier Dony <odony@users.noreply.github.com>