Add "poulp info"
This command will give infos about a specific package.
All the fields of the manifest should be displayed in an human-readable way. Example (not with all the fields):
✓ Installed
Name package
Version 0.1.0 (latest is 0.2.0, update with `poulp update package`)
Description This is a package.
Author John Doe
Contributors Jane Doe, Foo Bar
Files package.vapi, package.h, package.so, package.pc
Dependencies other (0.2.3), foo (<2.1.0), bar (*)
Website https://john.doe.eu/projects/package
Source code https://john.doe.eu/git/package.git