Add a system for regular and/or on-demand data dumps

[Oaphi]

meta:295094
meta:293597

Adding a tracking issue since it's been requested a couple of times and is a general expectation of our community members. It won't be an easy feat to implement properly, but we shouldn't lose sight of the request.

Related: meta:285446

[ArtOfCode-]

This is actually not as difficult as it appears at first. I've done both data dumping and live SQL data explorer elsewhere, effectively by whitelisting specific columns and using views to limit access.

[Oaphi]

Oh, that's nice! I haven't inspected Metasmoke's code in a while - this quite simplifies things

[Oaphi]

I suppose the main thing now is to decide what to include in the dump. There are some access control considerations - I presume we can only include public categories & related entities.

[cellio]

Related: #780