[validation] Check if @shortcut and @aliases are supported correctly... together

[l-trotta]

Here's SpanTermQuery, where value is both a shortcut and has an alias (yes it's correct):

/**
 * @shortcut_property value
 * @ext_doc_id query-dsl-span-term-query
 */
export class SpanTermQuery extends QueryBase {
  /** @aliases term */
  value: FieldValue
}

All flight recorder tests fail with this one, saying:

Type '{ _name: string; boost: number; value: string; }' is not assignable to type 'FieldValue | QueryDslSpanTermQuery | undefined'.

and

Property 'term' is missing in type '{ _name: string; boost: number; value: string; }' but required in type 'QueryDslSpanTermQuery'.

So it seems like the combination of shortcut and aliases breaks both

[pquentin]

The second error applies to all aliased mandatory properties. They're just added to the class and of course they can't all be mandatory.

elasticsearch-specification/typescript-generator/src/index.ts

Lines 203 to 209 in cdaa4ef

	for (const property of type.properties) {
	code += ` ${cleanPropertyName(property.name)}${required(property)}: ${buildValue(property.type, openGenerics)}\n`
	if (Array.isArray(property.aliases)) {
	for (const alias of property.aliases) {
	code += ` ${cleanPropertyName(alias)}${required(property)}: ${buildValue(property.type, openGenerics)}\n`
	}
	}

[pquentin]

We discussed this offline. There's a way to handle aliases in TypeScript: https://stackoverflow.com/questions/44425344/typescript-interface-with-xor-barstring-xor-cannumber. But it can quickly get messy when there are multiple aliases (either on multiple fields, or for fields with multiple aliases). It could actually impair debugging.