Refactor GQLFilterParser.Parse to take input BaseQueryStructure

[Aniruddh25]

Why make this change?

• This is a precursor to Cannot filter using fields in relationship #825 the design for which is discussed in Nested Filtering For MsSql Design #957.
• It is purely a refactor necessary to write a recursive graphql filter parser for SQL.

What is this change?

• Although many files seem to be changed, main file to focus on is GQLFilterParser.
• Change the input arguments for GQLFilterParser.Parse to include a BaseQueryStructure so that it can be called recursively for nested filters both for SQL and Cosmos. Currently, used only for Cosmos by setting the DatabaseObject.Name to parentSourceName.NestedFilterFieldname before each recursive call. Eventually resetting to _containerAlias once back to the first caller in CosmosQueryEngine
• With this modification, moved some of the properties from BaseSqlQueryStructure to the base class BaseQueryStructure which are useful for Cosmos too :
  • EntityName = the entity name from the config,
  • SourceAlias = the alias of the main entity being filtered used in the query that's generated (renamed from TableAlias). Is the containerAlias on the first instance of the call for Cosmos.
  • MetadataProvider = either the Sql or Cosmos metadata provider (renamed from SqlMetadataProvider)
  • DatabaseObject = has the schema name and source name
  • AuthorizationResolver = useful to add DbPolicyPredicates for any of the entities used in the nested filter
• Make GQLFilterParser a singleton service dependent on ISqlMetadataProvider since we will (in a future PR) use the information from the MetadataProvider to obtain DatabaseObject of the nested entity.
• Constructor modifications to trickle the GQLFilterParser and AuthorizationResolver to the BaseQueryStructure

How was this tested?

• Existing tests since this is only a refactor, no change in functionality.

[abhishekkumams]

LGTM

[ayush3797]

LGTM!

[aaronburtle]

Looks good!