Add Missing Encoder Check on Startup/Profile load

[derrod]

Description

Adds additional checks to the nvenc test binary, and uses it to show a descriptive error message on startup if NVENC was selected and is now missing.

Example:

Motivation and Context

Want to make it more obvious to users why NVENC has gone missing, especially those with Kepler GPUs.

How Has This Been Tested?

Tested with modifications to the nvenc test binary to produce various error codes.

Types of changes

• New feature (non-breaking change which adds functionality)

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.

[Warchamp7]

I'd like to adjust the formatting of this a little bit to group the errors with the encoder it's for

---

There were errors with one or more encoders:

obs_nvenc_hevc_tex

NVENC check failed with reason: Outdated driver (code: outdated_driver)

obs_nvenc_another

Miscellaneous probme (code: bad_nibbles)

See the Knowledge Base Article for further information

---

<li>
<h3></h3>
<code><code>
</li>

[derrod]

Updated it based on that, looks like this now:

[Warchamp7]

Updated it based on that, looks like this now:

Looks good aside from the code: outdated_driver getting double reported on the NVENC entries. Is NVENC including that as part of their error message?

[derrod]

Yeah the error string for NVENC originally included the code as well and I forgot to remove that.

See https://github.com/obsproject/obs-studio/pull/11340/files#diff-cd50d66da1e02db4fa473b80d6109b5799b4e619d09ac4e4487e4492ded51fc8R1604