Support built-in `project.el` for getting project name

[meliache]

Adds the functions activity-watch-project-name-project and activity-watch-project-name-project-force which use the built-in project.el package for getting the project name. Added it to the default list of resolvers behind projectile, because project.el is always available and when the user explicitly installs projectile for advanced functionality, projectile should be preferred. Added it in front of magit, because magit is no explicit project management package and thus should only be a fallback.

[meliache]

No problem, thanks for creating the package in the first place.