Fix minor voiceNext issue

[Licho1]

Description

This PR fixes issue, where if bot joins a channel that already has people, and those people speak, their voice stutters first time they talk and is ok next time.

It happens because discord sends player joined event only AFTER person stops speaking first time. This means we don't have entry in _transmittingSsrCs and current logic kept recreating it on every packet leading to wrong gap/invalid order packet logic.

This PR also fixes naming issues (which exists in current repo) be labeled as errors (problem in jetbrains rider for example) and fixes DiscordUser comparison for nullable references.

Also voice next native auto copies dlls to bin for easier local testing.

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

• Tested by using voice from the bot with another project.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules

[CLAassistant]

All committers have signed the CLA.

[Lulalaby]

The nullability is in rework in #341, but we accept it for now, since it doesn't harm.
Many thanks for taking the time for the annoying voicenext topic.