Add localization declaration for macOS builds of ardour

Community Ideas for Ardour
#1

Currently the macos app don’t declares supported language in the Info.plist,
which makes choosing language differ from system language more complex.

add these lines to the Info.plist can enable custom language selection.

	<key>CFBundleLocalizations</key>
	<array>
		<string>en</string>
		<string>ca</string>
		<string>cs</string>
		<string>de</string>
		<string>eu</string>
		<string>fr</string>
		<string>it</string>
		<string>ja</string>
		<string>ko</string>
		<string>ru</string>
		<string>sv</string>
		<string>zh</string>
	</array>
#2

While I like the idea of allowing macOS users to make per-app localization options, I’m not wild about the lack of full specifications here (eg. to differentiate Brasilian Portugese from Portugese Portugese).

#3

I used the gtk_ardour/appdata/po folder as a reference when making the snippet above.
( I have no knowledge about this.)

this time i used gtk_ardour/po/ as reference and this should contains all available languages.

	<key>CFBundleLocalizations</key>
	<array>
		<string>en</string>
		<string>ca</string>
		<string>cs</string>
		<string>de</string>
		<string>el</string>
		<string>en_GB</string>
		<string>es</string>
		<string>eu</string>
		<string>fr</string>
		<string>it</string>
		<string>ja</string>
		<string>ko</string>
		<string>nn</string>
		<string>pl</string>
		<string>pt</string>
		<string>pt_PT</string>
		<string>ru</string>
		<string>sv</string>
		<string>zh</string>
	</array>