Refactor error message handling

[Yury-Fridlyand]

What to change

• ErrorMessageFactory
• ErrorMessage
• OpenSearchErrorMessage

Reason

1. Those classes are duplicated - in :legacy for SQL and in :opensearch for PPL.
2. They are referred in two places:
   1. in ResponseFormatters in :protocol to format an exception, but this code never used
   2. in RestPPLQueryAction in :plugin to format a error for PPL and in RestSqlAction in :legacy to format a error in SQL
3. These classes add a dependency between :protocol and :opensearch.

Purpose

1. Break the dependency - this is needed for [FEATURE] Make OpenSearch function registered dynamically #811 (UDF = user defined functions)
2. Use formatters to format an exception

How to

1. Let OpenSearchExecutionEngine to extract data from OpenSearchErrorMessage and build a regular exception.
2. Move ErrorMessage to :protocol.
3. Delete ErrorMessageFactory since it is not needed anymore; copy unwrapCause to ErrorMessage.
4. See example in e66e6b9.