Add support for converting Any <-> ParamValue

[mjcarroll]

🎉 New feature

Summary

Add support for converting between gz::msgs::Any and rcl_interfaces/msg/ParameterValue.

This is used in support of MBZIRC's RF ranging sensor: osrf/mbzirc#151 to avoid adding custom messages that won't be supported by the bridge.
Both of these types use a "tagged union" approach to represent multiple datatypes within a single message.

Currently, the supported types have overlap for the most common types, but aren't identical. When an unsupported type is converted, the resulting message will be unpopulated.

Checklist

• Signed all commits for DCO
• Added tests
• Added example and/or tutorial
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if the library has them)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
• While waiting for a review on your PR, please help review another open pull request to support the maintainers

Note to maintainers: Remember to use Squash-Merge and edit the commit message to match the pull request summary while retaining Signed-off-by messages.

[chapulina]

LGTM, uncrustify is unhappy though