Add and test support for handling complex `attributeExpression`

[sarthak77]

In response to this discussion, adding support for complex attribute. This will work as a substitute for map attributes.

e.g In a correct request, the attribute is mapped to the map column, and QS can understand the subpath.

AttributeExpression {
attributeId: API_TRACE.tags";
subpath: "span.kind"
}

e.g In a bad request, the attribute is mapped to a long column, and QS can't understand the subpath for that column, so will throw an exception.

AttributeExpression {
attributeId: API_TRACE.startTime";
subpath: "1234"
}

Dividing it into the following subtasks :

• Add support for complex attributes in QueryRequestToPinotSQLConverter.java
• Add relevant tests in MigrationTest.java
• Pre process query request to add tags__KEYS = 'sample_column' filter