MD012: Additional triming for redundant trailing double space

[nschonni]

I've noticed in some places Prettier/remark will remove additional double spaces that Markdownlint won't flag. A maybe incorrect and non-exaustive list:

• On a blank link between list items
• At the end of a sentence followed by an empty line

I think these are just some extra edge cases that represent the end of blocks described in https://spec.commonmark.org/0.30/#hard-line-breaks but not shown in any of the tests