♻️ Parse entities to `text_special` token

[chrisjsewell]

Rather than adding directly to text. The text_join core rule then joins it to the text later, but after typographic rules have been applied.

Implements upstream: https://github.com/markdown-it/markdown-it/commita/3fc0deb38b5a8b2eb8f46c727cc4e299e5ae5f9c

[codecov[bot]]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.03 :tada:

Comparison is base (ea27cc8) 95.13% compared to head (4baa9ce) 95.16%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #280 +/- ## ========================================== + Coverage 95.13% 95.16% +0.03% ========================================== Files 64 64 Lines 3432 3434 +2 ========================================== + Hits 3265 3268 +3 + Misses 167 166 -1 ``` | Flag | Coverage Δ | | |---|---|---| | pytests | `95.16% <100.00%> (+0.03%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=executablebooks#carryforward-flags-in-the-pull-request-comment) to find out more. | [Impacted Files](https://app.codecov.io/gh/executablebooks/markdown-it-py/pull/280?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=executablebooks) | Coverage Δ | | |---|---|---| | [markdown\_it/rules\_inline/entity.py](https://app.codecov.io/gh/executablebooks/markdown-it-py/pull/280?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=executablebooks#diff-bWFya2Rvd25faXQvcnVsZXNfaW5saW5lL2VudGl0eS5weQ==) | `100.00% <100.00%> (ø)` | | ... and [1 file with indirect coverage changes](https://app.codecov.io/gh/executablebooks/markdown-it-py/pull/280/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=executablebooks)

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