Remove strum and strum_macros dependencies

[muzarski]

Ref: #771

Motivation

strum and strum_macros are unstable crates and their usages need to be removed from the public API to stabilize it.

These crates are responsible for generating FromStr implementations for the types.

Changes

Replaced strum usages for NativeType and ColumnKind types with our own implementations of FromStr.

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.

[piodul]

The semver checks job silently failed here for the reason described here: #936. It looks like /dev/tty very recently stopped being available in our job runner's environment.