bug: Basic authentication requests are case-insensitive both in scheme and parameters, but this isn't supported by APISIX

[reinvantveer]

Current Behavior

Lines like https://github.com/apache/apisix/blob/master/apisix/plugins/basic-auth.lua#L81 prescribe case-sensitive header keys and values but according to https://datatracker.ietf.org/doc/html/rfc7617#page-3 (scroll down a bit):

Note that both scheme and parameter names are matched case-
insensitively.

APISIX thus does not appear to follow the http spec (unless I'm missing something).

Some products such as Elasticsearch have addressed this issue

Thank you.

Expected Behavior

APISIX should listen to (and unit-test for)

• authorization: basic [etc.]
• Authorization: basic [etc.]
• authorization: Basic [etc.]
  Even:
• AuThOrIZaTIOn: bAsIC
  is a valid authorization header string start

Error Logs

No response

Steps to Reproduce

I'm unsure on what to write here. The code is in the default branch. I wrote a custom WASM plugin in Rust using the WASM SDK and it only pics up Basic literal request headers as valid authorization header, not basic.

Environment

This doesn't appear to be a version-specific thing.