add logic for wiki style links functionality

[tarpdalton]

This adds a feature where you can link to any page in site.Pages by just using [[page_you_want_to_link]].

• It will use the first match it finds, so you cannot have pages with the same Params.title
• It might affect build performance if there is a huge number of pages and wikilinks

These types of links are getting more popular with tools like roam, foam, obsidian, etc.

gohugoio/hugo#3606

[mo-nonym]

I guess a workaround would be to implement a CI pipeline which executes this python script on the content folder before building a page.