rtmp-services: Fix bugs blocking WHIP services

[iameli]

Description

Two small changes:

1. This fixes the code for populating Bearer tokens for WHIP services defined in services.json — previously there was a segfault when attempting to call rtmp_common_get_connect_info(data, OBS_SERVICE_CONNECT_INFO_BEARER_TOKEN). Shoutout to @Sean-Der to making this possible at all and @ImLunaHey for finding the fix!
2. WHIP services do not have an appropriate value for the deprecated output field. It wouldn't be correct for them to use a value like rtmp_output. I also didn't want to add an incorrect whip_output field to a deprecated enum? So I made output optional for services with protocol: WHIP. Not sure what the right answer is there.

Motivation and Context

Enabling WHIP services to be added to services.json, such as Streamplace.

How Has This Been Tested?

Tested by building and streaming using macOS 15.3.1 (in conjunction with #12032)

Checklist:

• My code has been run through clang-format.
• I have read the contributing document.
• My code is not on the master branch.
• The code has been tested.
• All commit messages are properly formatted and commits squashed where appropriate.
• I have included updates to all appropriate documentation.

[iameli]

Anything I could do to help get this prioritized?

[RytoEX]

This removes the requirement of the recommended field for services using WHIP. Why?

[RytoEX]

Never mind. I have re-read the change and the PR description. It's removing the requirement for the output key within the recommended key. I would have to investigate more to better understand what is "best" here.

[iameli]

I mentioned that as point #2 in my description - that field is deprecated and there's no appropriate value for WHIP services. The existing options are:

"rtmp_output",
"ffmpeg_hls_muxer",
"ffmpeg_mpegts_muxer"

WHIP is none of those. I could certainly add a value called whip_output in there, but it would be an additional enum on a deprecated field used by nothing and read by nobody. What's the point?

[iameli]

Oop, missed your reply, all good :)

[RytoEX]

Use the commit prefix rtmp-services: for both commits. Use Sentence case for the text after the prefix (Capitalize the first letter of the first word).

[iameli]

@RytoEX Done!