Add an ability to translate strings for exact post/page/article

[oglekler]

1. When strings are processing for translation, add information about where these strings are used on WordPress.org / Learn e.t.c. and their order on the page.
2. Add filter to search strings by page/post/article, where they are used to translating specific post/page and ability to sort them by 'native' order on the page.
3. Add link to translate current post/page/article to user's native language.

The implementation of this can be tricky, but I believe that these enhancements will be very useful, and the outcome is worth the effort. Right now to translate a specific page you need to search for each string from the original page that slowing the process. Otherwise, if you will be translating stings without context and order, the result can be patchy and vague for understanding.

This proposal can be split on several tickets to isolate different parts and achieve the end result by steps.

[tobifjellner]

The current solution at ​https://translate.wordpress.org/ uses po/mo files as the bearer of translations. This approach is the best for localization of software, where we need to adopt the UI to various locales/languages.

But our translation platform is NOT so good for translation of content, where we would need to translate a flowing text in context.

Since some time, I've started thinking that we need another solution for support/training/handbooks, etc.