codec-utils: support extension audio object type and sample rate

ISO 14496-3 defines that audioObjectType 5 is a special case that
indicates SBR is present and that an additional field has to be
parsed to find the true audioObjectType.

There are two ways of signaling SBR within an AAC stream - implicit
and explicit (see [1] section 4.2). When explicit signaling is used,
the presence of SBR data is signaled by means of the SBR
audioObjectType in the AudioSpecificConfig data.

Normally the sample rate is specified by an index into a
table of common sample rates. However index 0x0f is a special case
that indicates that the next 24 bits contain the real sample rate.

[1] https://www.telosalliance.com/support/A-closer-look-into-MPEG-4-High-Efficiency-AAC

Fixes #39
8 jobs for issue39-support-heaac in 32 minutes and 30 seconds (queued for 10 minutes and 42 seconds)