[Media ML] Support customization for single/double/triple clicks

Track clicks to determine whether they are single/double/triple
clicks. Run the customized implementations if they exist.
Added test cases in "Testing scenarios" section of
go/apex-media-server-testing

Bug: 149260441
Test: manually
Change-Id: Ifaf759a33443a742995df390eb81e332f9879932
2 files changed