Rename index to key for Map instances

[pimfm]

Good day, really enjoying your generator, thanks for the ease of use of this project. My colleagues found a small thing that could be improved:
This map

val explanations: Map<String, String>

is generated into this:

explanations: { [index: string]: string }

It would be really nice if this index name was actually 'key' to show the key/value relation.

I suspect this code has something to do with it, but am not familiar enough to offer you a pull reqest.

typescript-generator/typescript-generator-core/src/main/resources/helpers/jsonDeserialization.ts

Line 10 in 1d533d9

return (object: { [index: string]: T }) => __copyObject(object, itemCopyFn);

Hope you find the space to do this name adjustment. Thanks in advance

[vojtechhabarta]

Hello, actually it is mainly here:

typescript-generator/typescript-generator-core/src/main/java/cz/habarta/typescript/generator/TsType.java

Lines 172 to 187 in 219c671

	public static class IndexedArrayType extends TsType {
	public final TsType indexType;
	public final TsType elementType;
	public IndexedArrayType(TsType indexType, TsType elementType) {
	this.indexType = indexType;
	this.elementType = elementType;
	}
	@Override
	public String format(Settings settings) {
	return "{ [index: " + indexType.format(settings) + "]: " + elementType.format(settings) + " }";
	}
	}

This TypeScript feature is called Index Signatures (it was called Indexed Array in the past, I think) - https://www.typescriptlang.org/docs/handbook/2/objects.html#index-signatures. That's why there is usually index. But I agree that for many people key would be more clear.

It would be easy change but I am not sure.
There is also suggestion that Java Map should be generated as TypeScript Record (#706).