Fix up installer and third party notices

[sdatkinson]

Description

Add ThirdPartyNotices.txt with necessary notices about third-party software. Link to open on settings page of plugin:

PR Checklist

• Did you format your code using format.bash?
• Does the VST3 plugin pass all of the unit tests in the VST3PluginTestHost? (Download it as part of the VST3 SDK here.)
  • Windows
  • macOS
• [N] Does your PR add, remove, or rename any plugin parameters? If yes...
  • [N/A] Have you ensured that the plug-in unserializes correctly?
  • [N/A] Have you ensured that older versions of the plug-in load correctly? (See Unserialization.cpp.)
• [N] Does your PR add or remove any graphical assets? If yes, are they defined in config.h and added in the two required locations in main.rc?