Set up the BBFILES_DYNAMIC variable to include meta-python and move all
python recipes to the corresponding dynamic-layers directory. This
prevents failures to parse recipes if meta-python is not available.
Pick-to: 6.5
Fixes: QTBUG-113712
Change-Id: If26668e8d901c89be8527ff3951a00d739a89372
Reviewed-by: Samuli Piippo <samuli.piippo@qt.io>