Tags Normalization

[jleandroperez]

Details:

In this PR we're bringing over several enhancements introduced in this macOS Issue

• Encapsulates Tag Hash generation in a NSString extension
• Encapsulates Tag Name validation in a (new) NSString extension
• Updates Tag Lookup mechanism, so that comparison is based on Hash rather than on Strings. Details here!

@aerych Sir!! since you've validated the first part, mind taking a quick peek? (nothing big should have changed!!)
Thank you!!

/cc @dmsnell NOW we're talkin'! 😃

Ref. #824

Scenario: Note Editor

1. Checkout commit cd4f251
2. Press over the top right button to add a new Note
3. Press over the Tags Editor

• Verify that new tags can have at most 5 characters (this is for testing! actual limit is 256 char).
• Verify that special characters are allowed (parentheses, comma).
• Verify that pressing a space "commits" the text you've typed.

IMPORTANT: Length is enforced against encoded tag name. Using non alphanumeric characters will yield a much lower limit!

Scenario: Tags Editor

1. Checkout commit cd4f251
2. Press over the top left button to reveal the Tags Editor
3. Long press over any tag

• Verify that pressing Delete effectively removes the new Tag.
• Verify that pressing Rename allows you to edit the Tag Name (up to 5 characters, for testing purposes!).
• Verify that during a rename OP pressing spacebar "Commits" the edit.

IMPORTANT: Length is enforced against encoded tag name. Using non alphanumeric characters will yield a much lower limit!

Release

These changes do not require release notes.

[peril-automattic]

You can trigger an installable build for these changes by visiting CircleCI here.

[aerych]

Looks pretty good @jleandroperez :) I spotted one tiny thing and left a mention about it in the code. Other than that I think this is good to go.

Verify that new tags can have at most 5 characters

I was only able to add four characters so maybe an off by 1 issue somewhere?

[jleandroperez]

Thank you sir!!!