BitstreamExtractor: fix parameter set access after duplicates

- after storing a *PS in the parameter set manager, the object may be deleted
- retrieve a PS back after storing
- add more explicit warnings in comments
6 jobs for !1460 with paramset_access_fix in 13 minutes and 21 seconds (queued for 8 seconds)
latest detached
Status Name Job ID Coverage
  Build
passed build_macos #10365
macos

00:03:43

passed build_ubuntu1604 #10366
ubuntu1604

00:00:13

passed build_ubuntu1804 #10367
ubuntu1804

00:00:17

passed build_ubuntu1804-gcc8 #10368
ubuntu1804-gcc8

00:00:17

passed build_vc191x #10369
vc191x

00:08:37

passed build_vc192x #10370
vc192x

00:07:34