Summary:
<Ctrl> + <R_Click> opens document. This find doxygen comment using libclang and
dump each tags.
Now, it just support functions.
Test Plan:
1. Open document using <Ctrl> + <R_Click>.
2. Check that the document is correct.
Reviewers: ajwillia.ms
Differential Revision: https://phab.enlightenment.org/D4522