Combine Music/Sound event into single Audio event

[salianifo]

Only test on backup timelines, not backwards compatible!

Closes: #2082
Closes: #1306

This PR combines the Music and Sound events into a new Audio event. It will automatically read the old sound/music event formats and convert them into the new audio event format.

Features

• Named audio channels
  • Channel names do not need to already exist, they are created dynamically
  • Channel names may contain a-z A-Z 0-9 _ -, but they may not be only -
  • Default settings for fade, volume, audio bus, and loop can be configured for named channels in the Audio section of the Dialogic Settings page, or updated/added by clicking the favorite icon next to the channel name in the event itself
  • Selecting/typing a channel name with default settings will override the current settings when the channel dropdown loses focus
  • Playing audio on a channel that is already playing audio will cross-fade from the previous audio to the new audio
• One-Shot SFX channel
  • This channel is used for short sounds that don't need to be tracked
  • Can play as many audio files as needed simultaneously
• Sync with channel
  • Allows you to start an audio file at the same position as the currently playing audio on a different channel
  • Can be used for layered audio tracks
  • Cannot be used with WAV files imported using Ima-ADPCM compression due to a Godot bug
• Looping implemented for WAV files

Text Format

# Plays "file_path" on channel_name with settings in shortcodes,
# defaults for anything not in shortcodes
audio channel_name "file_path" [shortcodes]

# Plays "file_path" as a One-Shot SFX with the default settings
audio "file_path"

# Stops audio playing on channel_name
audio channel_name -

# Stops all One-Shot SFX
audio -

Missing Features

• Syntax highlighting for the text timeline editor
• Code completion for the text timeline editor

Additional Changes Made

• Dynamic options field now has a new ANY_VALID_STRING mode that accepts a validation_func in the extra_info paramter of the event editor build functions
  • Expected return for the validation function is a Dictionary with valid_text and error_tooltip as keys, which are both optional if the text is already valid
  • If valid_text exists in the return from the validation_func, the current_value will be updated

[Jowan-Spooner]

Notes on my changes for completeness:

• Removed the ability to change a channels defaults from the event. Instead just have a button to go to the audio settings
• Volume, Fade, Bus, Loop and Sync are now considered override settings. This makes the workflow with the channel defaults feel more logical.
• Added syntax highlighting and code completion
• Various stuff I did while working on this 🙈