core: improve SDP parser to support ICE media stream options / improve existing data structures cloning in the SDP parser

[zenichev]

Pre-Submission Checklist

• Commit message has the format required by CONTRIBUTING guide
• Commits are split per component (core, individual modules, libs, utils, ...)
• Each component has a single commit (if not, squash them into one commit)
• No commits to README files for modules (changes must be done to docbook files
  in doc/ subfolder, the README file is autogenerated)

Type Of Change

• Small bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds new functionality)
• Breaking change (fix or feature that would change existing functionality)

Checklist:

• PR should be backported to stable branches
• Tested changes locally
• Related to issue #XXXX (replace XXXX with an open issue number)

Description

Commits are separated per change dedication, even though they concern the same component.

• core: add support of ICE media options to SDP parser
• core: improve an existing data structures cloning in the SDP parser

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core: add support of ICE media options to SDP parser

In the current implementation only parsing of ICE candidate
attributes is supported, which makes it Possible to work
with ICE candidates and parameters specifically related per
candidate, but makes it Impossible to work
with ICE options of the media stream level (ICE options which
have an impact on the whole specific media stream).

ICE candidate attributes and ICE media options have different
dedication.

In order to target this matter, a new linked list is introduced
to store ICE media stream options.

Additionally, now when parsing media stream's attributes,
a couple of new helper functions have been introduced to
properly extract and store ICE media options:

• extract_ice_option()
• add_sdp_ice_opt()

The following extraction approaches are supported:

• multi-valued ICE options attribute (more than one value per a= header)
• one value per attribute (multiple a= headers with ICE options present)

Also now the way how a "zeroed" on-hold is detected is improved,
in case of the ICE (re)negotiation (when the connection address is equal
to '0.0.0.0', the media port is equal to '9' and ice-option 'trickle' is
present) the SDP is Not considered as an on-hold case, and it clearly
detects it's the ICE (re)negotiation (RFC 8840), which for e.g.
leads to a proper work of other side modules' functions (which use SDP
parser's data structures),
such as 'is_audio_on_hold()' from the textops.so module.

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core: improve existing data structures cloning in the SDP parser

It's been noticed that the cloning of SDP session(s) and
SDP stream(s) structures doesn't allocate the ICE candidate attributes,
nor it allocates (recently introduced) ICE media stream options.

In order to target this a couple of new functions have been introduced:

• clone_sdp_opt_attr()
• clone_sdp_ice_attr()

And additionally the following functions have been improved, in order to
properly clone/free ICE candidate attributes and (recently introduced)
ICE media stream options:

• clone_sdp_stream_cell()
• free_cloned_sdp_stream()
• free_sdp()
• print_sdp_stream()

Additionally for a proper new structure length calculation, the following
function is fixed:

• clone_sdp_session_cell()

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Tagging project members to review the changes: @miconda @henningw @linuxmaniac

[miconda]

Can be merged if no other comments.