[IMPROVEMENT] Add an option to write metadata through Vault KV v2 in Logical class

[YawKar]

Is your feature request related to a problem? Please describe.
There is a feature in Vault KV v2 that allows to store custom metadata for secrets. Would be very useful to support it: https://developer.hashicorp.com/vault/docs/secrets/kv/kv-v2/cookbook/custom-metadata

Describe the solution you'd like
Probably it takes to slightly change Logical::write methods to allow the "/metadata" segment without appending "/data". (

vault-java-driver/src/main/java/io/github/jopenlibs/vault/api/Logical.java

Lines 287 to 288 in 343b3e5

	.url(config.getAddress() + "/v1/" + adjustPathForReadOrWrite(path,
	config.getPrefixPathDepth(), operation))

)

Describe alternatives you've considered
Currently the only visible alternative is to use other libraries (though I don't know such a library)/plain http request.

Additional context
No additional context.