Address #3624

[cheatfate]

This PR requires:

1. Use new Content-Type header value parser. nim-chronos#302
2. Use new Content-Type parser. nim-presto#32

to be merged.

[github-actions]

Unit Test Results

       12 files  ±0       860 suites  ±0   1h 4m 43s ⏱️ - 9m 44s
  1 911 tests ±0    1 764 ✔️ ±0  147 💤 ±0  0 ❌ ±0 
10 341 runs  ±0  10 151 ✔️ ±0  190 💤 ±0  0 ❌ ±0 

Results for commit ddb3abb. ± Comparison against base commit 52b32c1.

♻️ This comment has been updated with latest results.

[etan-status]

Have not looked into the nim-http-utils changes thoroughly, but the submodule is updated to master so I guess those are already reviewed.

I did some checks re case-sensitive handling, and all seems correct ✅

RFC 2045

The type, subtype, and parameter names are not case sensitive. For
example, TEXT, Text, and TeXt are all equivalent top-level media
types. Parameter values are normally case sensitive, but sometimes
are interpreted in a case-insensitive fashion, depending on the
intended use. (For example, multipart boundaries are case-sensitive,
but the "access-type" parameter for message/External-body is not
case-sensitive.)

The new Chronos tests seem to cover the linked issue, so LGTM 👍