[service]: add new subcommand to examine the initial configuration

[VihasMakwana]

Description

Why is this useful?

• Users might want to examine the config if they face any errors at boot time. This subcommand prints the configuration on stdout after merging and resolving from all the --config sources.
• The command prints the configuration even if it's invalid. This can help user to track down the faulty piece of config.

Usage

./otelcorecol examine --config=file:file.yaml --config=http://remote:8080/config --config=file:file2.yaml

Link to tracking issue

Fixes ##11479

Testing

Added unit test cases.

Documentation

Updated readme.