Support CQL Vector type

[pkolaczk]

Fixes #1014

Pre-review checklist

• I have split my patch into logically separate commits.
• All commit messages clearly explain what they change and why.
• I added relevant tests for new features and bug fixes.
• All commits compile, pass static checks and pass test.
• PR description sums up the changes and reasons why they should be introduced.
• I have provided docstrings for the public items that I want to introduce.
• I have adjusted the documentation in ./docs/source/.
• I added appropriate Fixes: annotations to PR description.

[github-actions]

cargo semver-checks detected some API incompatibilities in this PR.
Checked commit: 9a19bbd

See the following report for details:

cargo semver-checks output

./scripts/semver-checks.sh --baseline-rev bbb28746d96720764e5e476ef7ce11ba3a00a36d
+ cargo semver-checks -p scylla -p scylla-cql --baseline-rev bbb28746d96720764e5e476ef7ce11ba3a00a36d
     Cloning bbb28746d96720764e5e476ef7ce11ba3a00a36d
     Parsing scylla v0.13.0 (current)
      Parsed [  24.448s] (current)
     Parsing scylla v0.13.0 (baseline)
      Parsed [  21.021s] (baseline)
    Checking scylla v0.13.0 -> v0.13.0 (no change)
     Checked [   0.078s] 79 checks: 78 pass, 1 fail, 0 warn, 0 skip

--- failure enum_variant_added: enum variant added on exhaustive enum ---

Description:
A publicly-visible enum without #[non_exhaustive] has a new variant.
        ref: https://doc.rust-lang.org/cargo/reference/semver.html#enum-variant-new
       impl: https://github.com/obi1kenobi/cargo-semver-checks/tree/v0.34.0/src/lints/enum_variant_added.ron

Failed in:
  variant CqlType:Vector in /home/runner/work/scylla-rust-driver/scylla-rust-driver/scylla/src/transport/topology.rs:239

     Summary semver requires new major version: 1 major and 0 minor checks failed
    Finished [  45.595s] scylla
     Parsing scylla-cql v0.2.0 (current)
      Parsed [  10.448s] (current)
     Parsing scylla-cql v0.2.0 (baseline)
      Parsed [  10.156s] (baseline)
    Checking scylla-cql v0.2.0 -> v0.2.0 (no change)
     Checked [   0.073s] 79 checks: 78 pass, 1 fail, 0 warn, 0 skip

--- failure enum_variant_added: enum variant added on exhaustive enum ---

Description:
A publicly-visible enum without #[non_exhaustive] has a new variant.
        ref: https://doc.rust-lang.org/cargo/reference/semver.html#enum-variant-new
       impl: https://github.com/obi1kenobi/cargo-semver-checks/tree/v0.34.0/src/lints/enum_variant_added.ron

Failed in:
  variant ColumnType:Vector in /home/runner/work/scylla-rust-driver/scylla-rust-driver/scylla-cql/src/frame/response/result.rs:75
  variant ParseError:InvalidCustomType in /home/runner/work/scylla-rust-driver/scylla-rust-driver/scylla-cql/src/frame/frame_errors.rs:51
  variant CqlValue:Vector in /home/runner/work/scylla-rust-driver/scylla-rust-driver/scylla-cql/src/frame/response/result.rs:101

     Summary semver requires new major version: 1 major and 0 minor checks failed
    Finished [  20.722s] scylla-cql
make: *** [Makefile:61: semver-rev] Error 1

[rukai]

Hi @pkolaczk I'm very happy for you to take on the final part of this work.
Since what I have in #1020 is quite small and includes tests, I'll keep responding to feedback there and hopefully merge it soon. After that it would be great to see your work land as a complete solution.

I also took some ideas from your PreCqlType implementation, thanks!

[rukai]

Heads up that while working with vector types I've discovered that even the official java driver has issues with them, it only supports vectors of int, long, float and double.

I've demonstrated the issues here: https://github.com/rukai/cassandra_vector_bug/blob/main/src/main/java/com/mycompany/app/App.java

[pkolaczk]

Heads up that while working with vector types I've discovered that even the official java driver has issues with them, it only supports vectors of int, long, float and double.

Internally only vectors of 32-bit floats are supported. This is what the index uses. There is no point in supporting other types in the driver at the moment.

[pkolaczk]

Can you give me a few hints on how do I add tests to this work so I can get this moving forward?
Also, is the other Vector branch going to be merged soon (that one has tests)? I'm fine just adding serde on top of that other branch if that one is close to being ready, rather than repeat the work on the tests here.

[hoxxep]

@pkolaczk I'm curious, do you have a microbenchmark that suggests this does anything different to a regular Vec<T> on release mode?