Stability changes for version 5.0.0

[amunra]

Overview

This PR is about introducing stability changes targeting the release of version 5.0.0.

Task list

• @javier: Updated front page doc and examples that are consistent across all clients.
• JSON-driven array tests
• Reword doc sections around protocol version, make it clear that selecting the protocol
  is only suggested for TCP and we advise "auto" for HTTP.
• Add a test for max_line_len from /settings (see point above).
• Introduce a new simpler array C API that doesn't require strides:
  line_sender_buffer_column_f64_arr_row_major (we will use this from Python).
• Investigate if the two APIs that take strides can be optimised further.
  You mentioned that these are slower than the equivalent Rust ndarray APIs.
• Consolidate array error codes into a single ArrayError code. These should be consolidated:
  • ArrayHasTooManyDims
  • ArrayViewError
  • ArrayWriteToBufferError
• Introduce a lower-level C++ API that just takes pointers and lengths for
  data and strides.
• Introduce an overloaded C++ API that just takes an array data pointer and
  length, and assumes default strides (calling _f64_arr_row_major).
• Fix warnings when generating docs with (cd questdb-rs && cargo doc --open)
  E.g.: warning: unresolved link to Sender::new_buffer_with_max_name_len.
• Add the C++ API change from PR Implement C++ line_sender::flush_and_keep_with_flags() #88
• Update and document (front page + examples + api docs) which is the first
  version of QuestDB supports arrays.
  My guess is that it is going to be 8.4.0, but we need to confirm this.
  (I've also added this todo to the Python client TODO list.)
• Improved C++ API ergonomics:
  • Lower-level API that is similar to the C API
  • Higher-level API that takes a vectors and spans in C++20.
• Once the next QuestDB release is cut, we should revert the CI hacks that test
  against the nd_arr branch. We should also retain a CI test run that runs
  against an older version of QuestDB (e.g. 8.3.3) to ensure that we don't
  introduce regressions against protocol version 1.

Tandem PR

See related py-questdb-client PR: questdb/py-questdb-client#108