ffi: Add support for serializing msgpack map using key-value pair IR format.

[LinZhihao-723]

Description

This PR implements the method to serialize msgpack maps using CLP key-value pair IR format. It includes the following component changes:

1. The core serialization method, which contains the traversal of a msgpack map.
2. Updates on CLP IR protocol to add support for the key-value pair format.
3. Serialization helpers that convert primitive values into encoded CLP IR byte sequences.

With this PR, the ffi should have all the functionality needed to serialize structured log events.

Validation performed

1. Add new unit tests to ensure the serialization method can successfully serialize msgpack maps that we support. Notice that deserialization cannot be validated until we have the deserializer formally implemented.
2. Using beta branch code to validate that the serialized data can be successfully deserialized and converted back to the original structured log event records.