Handle NaN and Infinity in JSON stringify function

Co-authored-by: Thaddeus Crews <repiteo@outlook.com>
Co-authored-by: Lukas Tenbrink <lukas.tenbrink@gmail.com>

doc/classes/JSON.xml

@@ -98,6 +98,7 @@
 				[b]Note:[/b] The JSON specification does not define integer or float types, but only a [i]number[/i] type. Therefore, converting a Variant to JSON text will convert all numerical values to [float] types.
 				[b]Note:[/b] If [param full_precision] is [code]true[/code], when stringifying floats, the unreliable digits are stringified in addition to the reliable digits to guarantee exact decoding.
 				The [param indent] parameter controls if and how something is indented; its contents will be used where there should be an indent in the output. Even spaces like [code]"   "[/code] will work. [code]\t[/code] and [code]\n[/code] can also be used for a tab indent, or to make a newline for each indent respectively.
+				[b]Warning:[/b] Non-finite numbers are not supported in JSON. Any occurrences of [constant @GDScript.INF] will be replaced with [code]1e99999[/code], and negative [constant @GDScript.INF] will be replaced with [code]-1e99999[/code], but they will be interpreted correctly as infinity by most JSON parsers. [constant @GDScript.NAN] will be replaced with [code]null[/code], and it will not be interpreted as NaN in JSON parsers. If you expect non-finite numbers, consider passing your data through [method from_native] first.
 				[b]Example output:[/b]
 				[codeblock]
 				## JSON.stringify(my_dictionary)