Implement the CharNormalizer trait on the LowercaseNormalizer struct

[Bradshaw]

Pull Request

Related issue

Fixes #239

What does this PR do?

• Implements CharNormalizer for LowercaseNormalizer
• Removes the previous Normalizer trait implementation
• Updates tests to include an initialized char_map field on the produced Token

PR checklist

Please check if your PR fulfills the following requirements:

• Does this PR fix an existing issue, or have you listed the changes applied in the PR description (and why they are needed)?
  • Yes, and as explained in Implement the CharNormalizer trait on the LowercaseNormalizer struct #239, it leads to a correctly populated char_map
• Have you read the contributing guidelines?
• Have you made sure that the title is accurate and descriptive of the changes?

Some quick notes

I based my implementation on CompatibilityDecompositionNormalizer.

This leads to duplicated code. I considered adding a function that both implementations could share, if that seems more appropriate, I can propose an alternate solution.

[Bradshaw]

Force-pushed to correct the use statements so they match the existing style.

[ManyTheFish]

Looks good to me!

Thank you @Bradshaw for your contribution,

have a nice day!

bors merge

[meili-bors]

Build succeeded:

• tests