Fixes https://github.com/go-gitea/gitea/issues/39770
`\(x^2\)is` and `\(x^2\)123` rendered as plain text because `\(...\)`
went through the same check on surrounding characters as `$...$`. That
check is there to skip things like `US$1`, which can't happen with
explicit `\(` `\)` delimiters, so it's now skipped for them, the same as
for "$`...`$". `$x$a` still isn't parsed.
Previously, recognition of escaped alert markers such as `\[!NOTE\]`
accidentally depended on enabling the optional `inline-parentheses` math
setting, resulting in such escaped alerts not rendering properly.
Goldmark splits the escaped marker differently based on the setting
being enabled or disabled, and only one form was handled. This commit
handles both forms.
For example, in a README or issue:
```
> \[!NOTE\]
> text
```
Before this commit, we'd get an ordinary blockquote displaying literal
`[!NOTE]` followed by `text`. With this commit, we get the styled
admonition.
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
Yunus Ozen