Make TimeZoneNames trimmable

[jnyrup]

With the switch to System.Text.Json in #85 we can further improve TimeZoneNames for NativeAOT applications by switching to a source generated TimeZoneData JSON deserializer.

Here's a POC on top of https://github.com/mattjohnsonpint/TimeZoneNames/tree/wip

Unfortunately System.Text.Json does not (yet) support init only properties, see dotnet/runtime#58770.

Here's some stats about the TimeZoneNames.NativeAot test application included in the linked POC.

main:
File size of TimeZoneNames.NativeAot.exe is 6091 KB
Crashes at runtime with

Unhandled Exception: System.TypeInitializationException: TypeInitialization_Type_NoTypeAvailable
	---> System.NotSupportedException: DeserializeNoConstructor, JsonConstructorAttribute, TimeZoneNames.TimeZoneData Path: $ | LineNumber: 0 | BytePositionInLine: 1.
	---> System.NotSupportedException: DeserializeNoConstructor, JsonConstructorAttribute, TimeZoneNames.TimeZoneData

POC:
File size of TimeZoneNames.NativeAot.exe is 4332 KB
Outputs TimeZone data to console at runtime.

[mattjohnsonpint]

Hi. Can you please reattempt this as a draft PR on top of the current main? Thanks.