All: Update builder dependencies

> grunt-cli   REMOVED

Not needed since grunt 1.x includes the 'grunt' command already.
Although even then, we weren't actually using this either (e.g. no
npm-scripts used in this repo).

> grunt         1.1.0  →    1.3.0

Ref <https://github.com/gruntjs/grunt/blob/v1.3.0/CHANGELOG>

* CoffeeScript bundling partially removed. Doesn't affect us afaik.
* Discovery of grunt plugins widened. Something to look out for since
  we do have a fairly complex pipeline, but afaik we only rely on
  local dependencies in the project directory, and we don't have other
  npm-based projects on the build server in parent directories so this
  should be fine as well.

> handlebars    4.7.6  →    4.7.7

Ref <https://github.com/handlebars-lang/handlebars.js/blob/v4.7.7/release-notes.md>

* This patch release makes note of a potentially breaking change to the
  an undocumented feature of accessing prototype properties in templates.
  Afaik we don't do this, so should be fine.

> lodash      4.17.15  →  4.17.21

Ref <https://github.com/lodash/lodash/wiki/Changelog>.

* Seemingly minor fixes. This repo only uses `lodash.identity()`
  and `lodash.find()`.

> semver        7.3.2  →    7.3.4 [ignored]

Ref <https://github.com/npm/node-semver/commits/v7.3.4>

Nothing that we need, and makes it no longer dependency-free
by bringing in `lru-cache`.

New (indirect) dependencies pulled in (see lockfile_:

* `async`
  <https://www.npmjs.com/package/async>

  Popular, well-known, well-maintained.

* "function-bind"
   <https://www.npmjs.com/package/function-bind> <https://github.com/Raynos/function-bind>
  "has" <https://www.npmjs.com/package/has> <https://github.com/tarruda/has>
  "is-core-module" <https://www.npmjs.com/package/is-core-module>

  Not commonly used directly, unfamiliar authors, tiny package,
  doesn't need to be used here. Comes in courtesy of:
  `grunt-cli` > `liftoff` (unmaintained) > `resolve`.
  Where `resolve` is mainly for Node <= 8 and for browserify, neither
  of which are applicable to liftoff or grunt, and resolve in turn
  brings in `is-core-module` > `has` > `function-bind`. Given liftoff
  is unmaintained, I guess we have no choice.

Author: Krinkle