[uri]decodebin3: Fix some stream selection issues

commit 22ac136d (HEAD -> user_selection, thiblahute/user_selection) Author: Thibault Saunier tsaunier@igalia.com Date: Fri May 22 00:35:03 2020 -0400

uridecodebin3: Let decodebin do its stream selection if no one answers

If no one answers our `select-stream` signal, uridecodebin3 should
behave the same way as `decodebin3` and let decodebin do its own stream
selection.

commit ab782292 Author: Thibault Saunier tsaunier@igalia.com Date: Fri May 22 00:32:15 2020 -0400

decodebin3: Avoid overriding explicit user selection

In case the user set a list of streams to select or answer explicitly
to all 'select-stream' event, we should respect his choice and not
try to add a stream per type.