* feat: adds alphabet generator

* We will be using that class in tests as well.

* feat: adds `custom` sort type

* feat: adds custom sort validation

* refactor: create function for each sort type

* test: adds tests for all rules

* The custom sort generated mimics `localeCompare()` for simplicity.
* I have added a single test with the `custom` sort type for each rule. I don't think that adding as many tests as other types is necessary: the objective is not to test that the behavior of a custom sort works for all rules, but rather to check that the rule handles that sorting type.
* Custom sorting behavior should be verified in `compare.ts`.

* refactor: moves some util files to `utils` folder

* docs: updates main pages

* docs: updates rules

* docs: improves style

* docs: fixes invalid documentation

* fix: fix invalid config creation

* fix: fixes typings

* refactor: [FEEDBACK] avoids using undefined

Co-authored-by: Azat S. <to@azat.io>

* refactor: [FEEDBACK] avoids using undefined

Co-authored-by: Azat S. <to@azat.io>

* refactor: [FEEDBACK] reduces comments length

* docs: [FEEDBACK] fixes missing `Alphabet`

* docs: [FEEDBACK] adds Astro section

* feat: [FEEDBACK] adds `convertBooleanToSign` function

* docs: added `Alphabet` documentation

- Removed `removeUnicodePlane` function, which is likely not that useful for users.

* build: [FEEDBACK] adds `eslint-plugin-perfectionist/alphabet` export

* docs: [FEEDBACK] adds `eslint-plugin-perfectionist/alphabet` export

* style: ESLint fix

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Co-authored-by: Azat S. <to@azat.io>