Use the ChannelIcon storage group in the services API Guide/GetChannelIcon()
(cherry picked from commit d21c685f62c58e596ce1ece86e85040285eb0ccd)
Add ChannelIcons to the list of "special" storage groups.

Signed-off-by: Raymond Wagner <rwagner@mythtv.org>
(cherry picked from commit d2316b47974f27dc333dd2924e8beb0aca92a73e)

Conflicts:

	mythtv/libs/libmythbase/storagegroup.cpp
decode URL before attempting to open them.

Thanks to Chris Pinkham for finding the root cause.

Fixes #11909

(cherry picked from commit cba3bc592f837b4680c2ec8075502b9323bdd3fe)
Revert "Add ChannelIcons to the list of "special" storage groups."

This reverts commit 88f380d100ca3e85c3ae26156eae8eb8b24400f6.

See 3d95e17
Fix services GetChannelIcon() when height or width are specified
(cherry picked from commit 15b82903a101eb2111889fb2c9600181f122dcce)