Bypass the threaded EvJobFind for EPUB documents and use WebKit's
WebKitFindController directly. The threaded find job was incompatible
with GepubDoc's single-threaded design and caused segfaults. The new
approach searches within the current page using WebKit's built-in text
search and highlighting, which is both simpler and thread-safe.

Assisted-by: OpenCode:claude-opus-4-6

origin commit:
https://github.com/linuxmint/xreader/commit/43acb8f

Added the required preprocessor directives to make building without epub support possible.

Added the function to handle links from the toolbar, also added functions to disconnect all ev-view handlers once it has been replaced by ev-web-view, and vice-versa(to drop all handler associated to ev-web-view).

Also the unref call to job_thumb was causing thumbnail jobs to crash with GTK2, so had to revert that, now we're back to the document folder not getting deleted from disk.

You can now search through the entire epub document. In the next commit I'm adding support for webkit2 with gtk3.

I added the capability to search through documents. The search is quite buggy, and we'll be taking care of each bug one at a time.

..and other fixing other bugs that were present once the webview was added, like the escape key command etc. Will look to refactor the thumbnails into ev-web-view.c.

In the next commit I'll extend this search over the entire document.Also will incorporate document index(table of contents).