Migrate remaining builds from Jenkins to Gitlab CI

Builds to Migrate

From Jenkins CI:

• cerbero android: still needed in addition to android-universal? nope
• cerbero android universal: done
• cerbero cross-mingw32: done
• cerbero cross-mingw64: done
• cerbero debian: #23 (moved)
  • deb package creation
• cerbero fedora: done
  • rpm package creation (currently broken and not tested, so out of scope for this issue, see cerbero#154)
• cerbero ios7-universal !138 (merged)
• cerbero osx-x86-64-1010: !133 (merged) (@ystreet)
• GStreamer master: done
• GStreamer distcheck: no longer needed after 1.16
• GStreamer master nodebug: done
• GStreamer master validate: done
• GStreamer master validate decodebin3: @thiblahute has it on his list
• GStreamer master validate adaptive: @thiblahute has it on his list

1.16 branch

• will be handled by gitlab CI going forward, same as master

1.14 branch

• jenkins 1.14 branch CI should be kept until 1.14.5 has been released (after 1.16)