misspell: support multiple correction words

[alexandear]

Allows to have multiple corrections.

extra-words.correction can accept either a single word or a list of words separated by commas:

linters-settings:
  misspell:
    extra-words:
      - typo: "iff"
        correction: "if"
      - typo: "successed"
        correction: "successful,success,succeeded"

When a misspelling is detected, the following lint message is displayed:

`successed` is a misspelling of `successful,success,succeeded`

However, during the fix process, only the first word in the list of corrections is used: "successed" is replaced with "successful".

The feature was requested in Slack discussion.

[ldez]

I declined this PR because misspell is made to match one word with another.

The fact of picking the first one proves that this is not adapted.

I can see several problems:

• it's a niche
• misspell was not designed for that

misspell is not a real typo detector, it's more an opiniated linter based on a set of known typos.
A known typo is a tuple of one misspelled word and one correction.
Because it's a misspelled word, the correction is also known.