[16.0][ADD] odoo_project_changelog: generate CHANGELOG of repositories/modules

[sebalix]

Supersedes #35

CHANGELOG generation feature

• list repositories on which you want to generate a changelog, with a source commit and an optional target commit (otherwise it'll fallback on last commit of branch)
• get a HTML report of relevant changes/commits for the repositories. This ignores translation commits and so on to get a readable changelog

"Generate CHANGELOG" button spawns jobs, "Refresh" button is then displayed

CHANGELOG ready

"Open CHANGELOG" button to get HTML report

Address issue #34