Move ng components from src/sidebar/directive to src/sidebar/components

Docs adrs tweaks

This makes the dir name match the type of object these modules export.

Convert element directives to components

Add ADR for adopting a component-based architecture for the UI

Query from url

 * Separate the 'Context' section into relevant background information
   and client-specific context.

 * Explicitly state in the 'Decision' section that `angular.component()`
   will be used.

This ADR provides an explicit write-up of how the UI is structured and
describes some changes we can make to the client to make this structure
more obvious and eliminate inconsistencies.

Components should use `bindings` rather than `scope` to declare inputs
and outputs.

Several directives should be registered as components but will require
refactoring before this is possible.

As part of an effort to make it clearer how the client uses Angular,
register UI components with `component()` instead of `directive()`.

Components in Angular 1.x [1] are essentially directives with "best
practices" defaults set (restricted to elements, isolated scope, bound
to controller) and deprecated/discouraged features of $compile
disallowed. These defaults/restrictions match how we are already using
Angular for most UI components.

[1] See https://docs.angularjs.org/guide/component

Correct the title of the documentation

Flesh out the docs for building the docs

URL queries should now use uri encoded strings for all default filter queries.

Fix client failing to load on pages that define `self`

Make these more user friendly and helpful, less knowledge assumed, but
still very terse.

Update README