assert.deepEqual and assert.deepStrictEqual currently return true for
any pair of Maps and Sets regardless of content. This patch adds
support in deepEqual and deepStrictEqual to verify the contents of Maps
and Sets.

Unfortunately because there's no way to pairwise fetch set values or map
values which are equivalent but not reference-equal, this change
currently only supports reference equality checking in set values and
map key values. Equivalence checking could be done, but it would be an
O(n^2) operation, and worse, it would get slower exponentially if maps
and sets were nested.

Note that this change breaks compatibility with previous versions of
deepEqual and deepStrictEqual if consumers were depending on all maps
and sets to be seen as equivalent. The old behaviour was never
documented, but nevertheless there are certainly some tests out there
which depend on it.

Support has stalled because the assert API was frozen, but was recently
unfrozen in CTC#63

Fixes: nodejs#2309
Refs: tape-testing/tape#342
Refs: nodejs#2315
Refs: nodejs/CTC#63

Updated PR based on comments

Ref: nodejs#12142

This change updates the checks for deep equality checking on Map and Set
to check all set values / all map keys to see if any of them match the
expected result.

This change is much slower, but based on the conversation in the pull
request its probably the right approach.

Ref: nodejs#12142

Cleaned up as per comments in issue

Ref: nodejs#6416

Based on comments in the PR, this change restricts an O(n^2) to only
happen when your set contains object-like objects, your map contains
object-like keys or you're not in strict mode.

ref: nodejs#12142 (review)

ref: https://github.com/nodejs/node/pull/12142/files/8fb6ebf9745badfb2f3f6a72cef211ff8bfbf6ba

Ref: nodejs#12142

- Added changes: entries in assert API documentation
- Refactored setEquiv based on @joyeecheung's comments

ref: nodejs#12142

ref: nodejs#12142

Refactored setEquiv and mapEquiv based on @joyeecheung's stylistic
preference to avoid labels.