Store the origin plugin when installing another plugin from the family

[MathieuLamiot]

Context
See #16
We want to track from which plugin of the family a user installed another plugin. For instance, if someone installs RankMath from the Imagify cross-sell tab, we want to keep track of this information in the DB.

Expected behavior
When installing a plugin aaa from plugin bbb through the plugin-family cross-sell buttons, we must store in the database of the website the fact that bbb was installed from aaa.

Acceptance Criteria
Exact AC depends on how this will be implemented.
Install Imagify with this version of plugin-family, on a website without RankMath. Install RankMAth through the plugin family button. Check the database: the information that seo-by-rank-math was installed from imagify must be there.
Then, uninstall RankMath. Install WP Rocket (with this version of plugin family). Install RankMAth through the plugin family button. Check the database: the information that seo-by-rank-math was installed from wp-rocket must be there, with no more reference to Imagify.

Additional information
We can use a WP option for instance. The suggested format here is that, for each install, we add (or replace if already existing) the option plugin_family_aaa_from and set its value to bbb