feat: add core HTTP data types

[algebraic-dev]

This PR introduces the core HTTP data types: Request, Response, Status, Version, and Method. Currently, URIs are represented as String and headers as HashMap String (Array String). These are placeholders, future PRs will replace them with strict implementations.

This contains the same code as #10478, divided into separate pieces to facilitate easier review.

The pieces of this feature are:

• Core data structures: feat: add core HTTP data types #12126
• Headers: feat: introduce Headers data type for HTTP #12127
• URI: feat: introduce URI data type for HTTP #12128
• Body: feat: introduce Body type class and some Body types for HTTP #12144
• H1: feat: introduce HTTP/1.1 protocol state machine #12146
• Server: feat: introduce HTTP/1.1 server #12151
• Client:

[ghost]

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[leanprover-bot]

Reference manual CI status:

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[Rob23oba]

Looks mostly good with a couple of small improvements

[mathlib-lean-pr-testing]

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[ericlesaquiles]

I'm looking into using this for a project of mine (I just need simple http requesting, actually).
Is there something I could do to help with this PR (and the other related ones)?
Cheers

[algebraic-dev]

@ericlesaquiles It’s almost at a stage where it will only need some adjustments, so I think taking a look at the code and checking if anything is missing or if anything is incorrect would be really helpful! :) If you need any guidance on the code, I can provide it.