feat!: expose classes of package audioplayers_platform_interface

[Gustl22]

Description

• move files of audioplayers_platform_interface into src folder
• export files to expose classes in audioplayers_platform_interface.dart

Checklist

• The title of my PR starts with a [Conventional Commit] prefix (fix:, feat:, docs:, chore: etc).
• I have read the [Contributor Guide] and followed the process outlined for submitting PRs.
• I have updated/added tests for ALL new/updated/fixed functionality.
• I have updated/added relevant documentation and added dartdoc comments with ///, where necessary.
• I have updated/added relevant examples in [example].

Breaking Change

• Yes, this is a breaking change. But not for the main audioplayers package.
• No, this is not a breaking change.

Migration instructions

Exposed classes in audioplayers_platform_interface:

Before:

import 'package:audioplayers_platform_interface/api/audio_context.dart';
import 'package:audioplayers_platform_interface/api/for_player.dart';
import 'package:audioplayers_platform_interface/api/log_level.dart';
import 'package:audioplayers_platform_interface/api/player_mode.dart';
import 'package:audioplayers_platform_interface/api/player_state.dart';
import 'package:audioplayers_platform_interface/api/release_mode.dart';
import 'package:audioplayers_platform_interface/streams_interface.dart';
import 'package:audioplayers_platform_interface/global_platform_interface.dart';

After:

import 'package:audioplayers_platform_interface/audioplayers_platform_interface.dart';

Internal classes in audioplayers_platform_interface:

Before:

import 'package:audioplayers_platform_interface/method_channel_interface.dart';
import 'package:audioplayers_platform_interface/api/audio_context_config.dart';

After:

import 'package:audioplayers_platform_interface/src/method_channel_interface.dart';
import 'package:audioplayers_platform_interface/src/api/audio_context_config.dart';

Related Issues

#1352