fix: crash on deinit() #68 and parameters retention after deinit()

[alnitak]

Description

Fixes for #68:

• AAudio disabled in favor of OpenSL for Android <= 29
• added PlayerErrors.playerAlreadyInited exception from cpp
• tests.dart updated to check sync/async init()-deinit()

Fix for parameters retention after deinit()

• after calling deinit() and then init() again, some player parameters like the max active voice count, was persisting. player.cpp has been updated to prevent this.

Type of Change

• ✨ New feature (non-breaking change which adds functionality)
• 🛠️ Bug fix (non-breaking change which fixes an issue)
• ❌ Breaking change (fix or feature that would cause existing functionality to change)
• 🧹 Code refactor
• ✅ Build configuration change
• 📝 Documentation
• 🗑️ Chore

[filiph]

LGTM!