Add autofix to selector-list-comma-newline-after

[ota-meshi]

Which issue, if any, is this issue related to?

Closes #3409

Closes #3421 (PR)

Is there anything in the PR that needs further explanation?

e.g.

• option always

  code:

  a,b {}

  fixed:

  a,
  b {}

  code:

  a, /* comment */ b {}

  fixed:

  a, /* comment */
  b {}

• option never

  code:

  a,
  b {
  }

  fixed:

  a,b {
  }

[jeddy3]

LGTM.

@ota-meshi You're on fire with these autofix additions :)

[ntwb]

Changelog 29424d4

Added: selector-list-comma-newline-after autofix (#3815).