Remove Inflector

[kazk]

• Use simple pluralizer (a Rust port of a popular JavaScript package plur minus the irregular and case matching)
• Duplicate the code in kube-derive without the special casing because it's short enough and didn't want to make this public. If necessary, I can publish the version in kube-derive as a separate crate.

This may be a breaking change if a user is using some kind that results in different plural.

Closes #470.

[clux]

awesome! looks clean, tests looks good.

[clux]

not sure if this is worth a line in the CHANGELOG. It's another potential breaking change, but very unlikely.

[clux]

Added some special cases from the upgraded dynamic_api example so it's now:

    if word == "endpoints" || word == "endpointslices" {
        return word.to_owned();
    } else if word == "nodemetrics" {
        return "nodes".to_owned();
    } else if word == "podmetrics" {
        return "pods".to_owned();
    }

[kazk]

I didn't see EndpointSlices kind in swagger.json. It had EndpointSlice kind and endpointslices path which I included in the test. Inflector failed that because of a buggy regex producing endpointsliceice. See https://github.com/whatisinternet/Inflector/pull/73/files#diff-fe8b9a2affc38f7fe10a95dc94e6e47ad21487ff46e2aea9aea8573604d9730eL45

[clux]

Released in 0.52.0 \o/