Add support for security barrier and invoker

[calebhearth]

Postgres accepts arguments in the form WITH (<option>[ = <true|false>]), so
rather than manually extending the various APIs to accept them individually
let's take a with: {...} argument that can take in arbitrary values.

The argument handling is:

• false or null values are discarded as the default behavior
• true values are passed as <option> = true
• other String or Symbol values are passed as <option> = <value>

This provides a more extensible API that can support any PostgreSQL view option
without requiring changes to Scenic's code, as evidence has shown that Derek and
I aren't super responsive maintainers. This should allow extensibility with new
Postgres (and other) features without requiring one of us to add support for
them.

A drawback and/or strength of this approach is that maintainers of Scenic
adapters such as MySQL or SQLite¹ will have to deal with the
with hash individually, and that it may break migrations between databases. I
suspect that the latter is (a). unlikely to ever come up and (b). the least of the
worries of developers who undertake this.

• Add parse_view_options helper to generically parse PostgreSQL reloptions

Conventional: Feat
Feat: Allow with argument to *_view to be passed to view DDL statements
Conventional: BREAKING CHANGE
Breaking: Users of the #433 fork will
need to adjust their arguments slightly.
Closes: #433
Closes: #432

Footnotes

1. I just want to call out that "SQLite" is intended to be
   pronounced as rhyming with meteorite and not with blight because I think that's
   fun. ↩