Add MediaProjection session to ContextualSearch Intent

When launching the ContextualSearch target, the Intent also contains a
valid MediaProjection token. This can be used to call
MediaProjectionManager#getProjection.

Bug: 395054309
Flag: android.app.contextualsearch.flags.contextual_search_media_projection
Test: atest ContextualSearchManagerTest
Change-Id: I2fb296de1cd5ac734798e04abb9c8c24b39a6e0b