Define asset lifespan via logs

Add a concept of "lifespan" to assets, similar to "location", "group membership", etc - and allow it to be tracked via logs. So one log can define the start of an asset's life, and one can define the end.

Old summary:

(The following is the old summary of this issue. See #2934961: Change asset "active" property to "archived" → for insight into how/why this changed.)

Currently assets are marked as "active" or "inactive" via a checkbox when you edit the asset. This serves the most-basic purpose of showing/hiding assets in farmOS (so you can hide old plantings, for example) - but it's not very advanced.

Ideally, the "active" status of an asset would be determined by logs - similar to it's location. In other words, when you log an activity (and/or other log types) on an asset, you should have the ability to change the status of the asset along with that log. If you had multiple logs affecting the asset's status, the most recent one would be the determining factor (just like location determination via movement logs).