fix(build/parser): parse empty string args for macros as Nones

[yin1999]

Description

replace empty string args for macos with Nones

Motivation

In mdn/content, we are used to use empty string to represent the argument is not provided, which should be None instead of Some(EmptyString). But we have use some judgement like if let Some(anchor) = anchor to check if the string argument is provided. This will evaluate to true as the judgement encounters a string.

I found an incorrect case in /en-US/docs/Mozilla/Add-ons/WebExtensions/API/pageAction/onClicked page:

There is a hash symbol at the end of the link text.

I think the easiest solution is to replace the empty string args with Nones. As we use similar logic to the above to determine whether the parameters are provided in many macos. Some cases (Maybe not all of them):

• crates/rari-doc/src/templ/templs/links/domxref.rs (we have checked whether the arg is an empty string)
• crates/rari-doc/src/templ/templs/links/htmlxref.rs
• crates/rari-doc/src/templ/templs/links/http.rs
• crates/rari-doc/src/templ/templs/links/jsxref.rs
• crates/rari-doc/src/templ/templs/links/webextapixref.rs (the one I found the issue)

I haven't fully tested this change, so I'm not sure if it will break any pages. If you have any ideas, please let me know.

[fiji-flo]

Thanks for this. I opened a PR yin1999#1 to move the logic into the actual parser. Please take a look and merge.