Pause menu functionality (#89)

* make menu use actual soundsettings values
* allow changing volume in pause menu
* persist saving settings

crates/hedz_reloaded/Cargo.toml

@@ -31,6 +31,7 @@ bevy_asset_loader = { workspace = true }
 bevy_ballistic = { workspace = true }
 bevy_common_assets = { workspace = true }
 bevy_debug_log = { workspace = true }
+bevy_pkv = { workspace = true }
 bevy_replicon = { workspace = true }
 bevy_replicon_renet = { workspace = true }
 bevy_sprite3d = { workspace = true }