add enum values for Metric and IndexMetrics path params

[ketkee-aryamane]

Linked to #360
adds enums for Metrics and IndexMetrics for node stats endpoint

Added the enum values by referring the 8.19 docs

[github-actions]

Following you can find the validation changes against the target branch for the API.

API	Status	Request	Response
nodes.stats	🔴	58/58 → 51/58	21/58

You can validate this API yourself by using the make validate target.

[flobernd]

Wondering if this case is similar to @pquentin recent related PR in a way that the server accepts combinations of multiple of these enum values (flags).

We should define an alias:
SomeMetricFlags = SomeMetricEnum | SomeMetricEnum[]

if that's the case.

[pquentin]

Sorry, as discussed offline last week, I did not know that you were working on fixing those APIs. I did it for another reason, namely #5215.

That said, on the docs side, we also need descriptions of the enum values. This documented enum:

elasticsearch-specification/specification/_types/common.ts

Lines 193 to 207 in 4d3b72e

	/**
	* Type of index that wildcard expressions can match.
	*/
	export enum ExpandWildcard {
	/** Match any data stream or index, including hidden ones. */
	all,
	/** Match open, non-hidden indices. Also matches any non-hidden data stream. */
	open,
	/** Match closed, non-hidden indices. Also matches any non-hidden data stream. Data streams cannot be closed. */
	closed,
	/** Match hidden data streams and hidden indices. Must be combined with `open`, `closed`, or `both`. */
	hidden,
	/** Wildcard expressions are not accepted. */
	none
	}

renders like this:

[pquentin]

This enum is not used. But I already defined it as NodeStatsMetric in specification/nodes/stats/NodesStatsRequest.ts anyway, with a few values that were missing in the 8.x docs so far.

[pquentin]

CommonStatsFlag is the name of the enum in the server code, so that was already correct. (Your version is also missing _all that is accepted by the server too.)