`http_version` option for a set of functions in

Related dev. issue(s): https://github.com/tarantool/tarantool/issues/9806

Product: Tarantool
Since: 3.1
Root document: https://www.tarantool.io/en/doc/latest/reference/reference_lua/http/
SME: @ Col-Waltz

Details

http.client module.

The http_version option allows to set version of http in functions like
request(), post(), get() and etc using this curl option:
https://curl.se/libcurl/c/CURLOPT_HTTP_VERSION.html
The http_version takes one of the strings listed below or a nil value
and sets the appropriate protocol version.

List of supported values:

1. nil - works as '2-tls' by default.
2. '1.1' - sets HTTP/1.1 version.
3. '2' - sets HTTP/2 version that falls back to HTTP/1.1 if cannot be
   negotiated with the server.
4. '2-tls' - works as '2' for HTTPS and as '1.1' for plain text HTTP.
5. '2-prior-knowledge' sets HTTP/2 version without HTTP/1.1 at back.
   It requires prior knowledge that the server supports HTTP/2.
   Requested by @ Col-Waltz in https://github.com/tarantool/tarantool/commit/c3695de1468f860229e04002786c1da11d76ce08.

Start with the linked HTTP client reference document and locate the entries for request(), post(), get(), and related functions. Document the http_version option, its accepted values, defaults, and HTTP/HTTPS behavior; the work is done when the reference accurately covers the listed protocol versions.