Swift implementation (IOS Equalizer)

[SimoneBressan]

I have opened this PR to trace the development of the implementation in swift and to give the possibility to use the equalizer in both platforms.

The goal now is to complete this implementation 100%!

You can use this package by pointing to the git repository.

  just_audio:
    git:
      url: https://github.com/Kuama-IT/just_audio.git
      ref: swift_implementation
      path: just_audio

No changes other than the original package are needed to make the project work. Follow the documentation.

It is not stable and it is not complete. Any contribution is welcome. This branch originated from wavy-assistant branch. Previous PR: https://github.com/ryanheise/just_audio/pull/658

RelatedIssue: https://github.com/ryanheise/just_audio/issues/334

Basic Features:

• [x] play
• [x] pause
• [ ] stop
• [x] seek seekToNext seekToPrevious
• [x] setVolume
• [ ] setSkipSilenceEnabled
• [x] setSpeed
• [x] setLoopMode
• [x] setShuffleModeEnabled
• [ ] shuffle
• [ ] setAutomaticallyWaitsToMinimizeStalling
• [ ] setCanUseNetworkResourcesForLiveStreamingWhilePaused
• [ ] setClip
• [ ] setPitch
• [ ] setPreferredPeakBitRate

Media Supports:

• [ ] Assets
• [x] Ipod-library
• [ ] Web url
• [x] Local file

Equalizer:

• [x] Ios
• [x] Android

Extra:

• [x] Support switch output device

Future features:

• [ ] Add default mixer presets (bassbost, voice and more)
• [ ] Manage many audio source
• [ ] Apply presets to specific audio source
• [ ] Save audio stream to file
• [ ] Stream audio stream to server