[attribute] add TabularData support

[yannmh]

Original discussion thread: #111
Credits to @brothhaar. Thanks a lot !!! 🙇

JMX TabularData support

Copied from #111, @brothhaar.

When a TabularData type is encountered, multiple metrics are generated with the same alias, but a unique tag per entry.
The tag is generated by concatenating each of the (possibly multiple) key values for each CompositeData entry in the TabularData JMX value
Also included limit and sort capability to allow sorting and limiting the number of metrics returned for a single configuration entry (since a TabularData value could have many records).
YAML config format:

- include:
  domain: <domain>
  bean:
    - <bean name>
  attribute:
    <TabularData attribute name>:
      metric_type: <type>
      alias: <alias>
      tags:
        <tag name>: $key
      limit: 20
      sort: desc

Additional changes

Allow tag substitution for any key of a TabularData object

Do not restrain tag substitution to the TabularType index. Instead, tag subtitution can be performed on any keys of a CompositeType.

For example:

Tabulardata.foo:
    metric_type: gauge
    alias: multiattr.foo
    tags:
      foo: $foo
      toto: $toto
    limit: 1
    sort: desc

instruments JMXFetch to collect a multiattr.foo metric tagged with foo and toto keys, where foo and toto are CompositeType keys.

Others

• Modify tests to use sort and limit for TabularData
• Rename JMXMultiAttribute to JMXTabularAttribute

[brothhaar]

👍 Looks good @yannmh. Thanks for taking the time to pull this in!