Smarter media re-initialization on call refresh with SDP re-offer/answer

[nanang]

Always re-initializing the media on call refresh can be annoying, especially for a call with video as video re-init may take several seconds.

Thanks Matynka Bartosz for the feedback.

[nanang]

In 4254:

Close #1568:

• Added media change detection based on SDP negotiation result and local codec param settings, the detection result will decide whether the media should be re-initialized after the SDP negotiation.
• Fixed stream to keep the duplicate of codec param for the stream info (was only copying the pointer).
• Introduced macro PJSUA_THIRD_PARTY_STREAM_HAS_GET_INFO & PJSUA_THIRD_PARTY_STREAM_HAS_GET_STAT.

[ming]

In 4265:

Re #1568: Add build config for SILK

[nanang]

In 4329:

Re #1568: backported to 1.x branch.

[ming]

In 4334:

Re #1568: Fixed is_media_changed() detection when pjsua_media_cfg.no_vad is set to PJ_TRUE and fixed the string duplication of encoding name
Thanks to Hideo and Fredrik for the reports.

[ming]

In 4336:

Re #1568: (PJSIP 2.x) Apply pjsua_media_config before detecting media change and fixed encoding name string duplication.

[ming]

In 4337:

Re #1568: (PJSIP 1.x) Apply pjsua_media_config before detecting media change

[nanang]

In 4338:

Re #1568: (only for 1.x) media transport should be (re)started even when media is unchanged.

[nanang]

In 4345:

Re #1568: (PJSIP 2.x) No need to restart media when remote RTP address changed but ICE transport is running.

[nanang]

In 4346:

Re #1568: (PJSIP 1.x) No need to restart media when remote RTP address changed but ICE transport is running.