Relevant references:
 RFC7231 Section 6.2.1
 RFC2518
 RFC8297

This affects several modules downstream that use the http
module, e.g., node-fetch, all of whom violate HTTP RFCs
due to this module. As such, this could introduce a
breaking change for downstream if HTTP standards were
ignored in an ad-hoc fashion.

101 Upgrade is excluded due to its non-informational
processing according to RFC7231, Section 6.2.2.

Lint is clean.

Must be distinct from `continue` event due to slightly different
behavior/triggering rules from 102/103 status codes. For example,
103 is explicitly made to take headers for pre-processing while 100
status codes never include headers.

`writeContinue` is highly specific to 100 status codes and sets state
for further processing. For example, keep-alive behavior is changed by
100 responses. `writeContinue` also cannot set header values, needed by
103 responses (so far).

Since 103 is affected by this patch, added test. 104-199 is not yet
defined, so leaving behavior undefined with no explicit tests.

* Replace v10.0.0 with REPLACEME in the http documentation
* Removed `_writeInformation`
* Removed test copyright header
* Removed `process.exit` from test

HTTP/2 changes will be done in a separate PR.

* While rebasing, old content resurfaced. Re-removed.
* Removed errant 'client' comment
* Removed assert descriptions
* Used common/countdown instead of simple int
* Capitalized initial letter in example comment