Add Support for Multiple Attributes

[Mrod1598]

Is your feature request related to a problem? Please describe.
Add Ability to pass in multiple Attributes into one otel.instrument() call.

Describe the solution you'd like
What I propose is adding additional signatures to otel.instrument that support attributes in the format of Map<String, Map<String,String>> where the strings represent <Attribute, <LabelKey, LabelValue>>

Example:
currently what is required to collect this metric

otel.instrument(beantomcatconnectors, "tomcat.threads.idle", "description", "1",
    ["proto_handler" : { mbean -> mbean.name().getKeyProperty("name") }],
    "currentThreadCount", otel.&doubleValueObserver)
otel.instrument(beantomcatconnectors, "tomcat.threads.busy", "description", "1", 
    ["proto_handler" : { mbean -> mbean.name().getKeyProperty("name") }],
    "currentThreadsBusy", otel.&doubleValueObserver)

What it would like with the proposed solution

otel.instrument(beantomcatconnectors, "tomcat.threads", "description", "1",
    ["proto_handler" : { mbean -> mbean.name().getKeyProperty("name") }],
    ["currentThreadCount": ["Thread Type": "current"],
    "currentThreadsBusy": ["Thread Type": "busy"]], 
    otel.&doubleValueObserver)

[rmfitzpatrick]

@Mrod1598 I can see the use of this feature and think it can be helpful. Wouldn't we want the attributes to map to label functions to keep with the current convention? Otherwise we seem to be limiting the capabilities out of the gate imo.