core: Add unit test for LogEventSerializer.

[haiqi96]

References

Description

Added unit test for LogEventSerializer and Deserializer

The unit test does the following:

1. Encode two log events into an IR file
2. Decodes the two log events from the IR file and convert them to plain text log message
3. Verify that the encoded log_events and decoded log events are identical

Validation performed

New test is added to the unit test and passed

[LinZhihao-723]

Before adding review comments, I think it's worth discussing the high-level concern here. The changes in decoding_methods.hpp/cpp should be moved to another PR for the following reasons:

1. The code added in this PR is duplicating generic_deserialize_log_event. The method itself is quite useful though (both javascript ffi and IR v2 require such a deserialize function). But we shouldn't simply duplicate code to create another function.
2. The current namings are quite confusing. We should distinguish which of these methods are deserialize_xxx, decode_xxx, and deserialize_and_decode_xxx respectively. In this PR, we have two overloaded deserialize_log_event, but they are not doing the same thing.

[LinZhihao-723]

I will prefer to rewrite the test case to have log events to serialize stored in a vector (push whatever u have right now), and just loop through the vector for serialization/deserialization. The enumeration in this test case seems too verbose