FIX: Insert bug for SqlCe when entity has Id that is a dynamic type for latest version of Dapper (v1.34)

- Optimized insert logic for identity fields to now use ExecuteScalar<long> instead of Query<long>
- For dialects that do not support multiple statements (SqlCe) - do not need to pass in the entity when executing the 2nd statement that retrieves the server generated identity key.  When Dapper sees the SQL statement that has an "@" (in this case, "@@identity") and a passed in entity for the 2nd arg, it tries to parse the entity, and will fail if entity has a dynamic Id key.  This used to work in previous version of Dapper (v1.26) but fails with current version (v1.34).  Possibly related to this issue https://github.com/StackExchange/dapper-dot-net/issues/130
- Added integration tests cases for SqlCe, SqlLite, & SqlServer for entity with dynamic Id field
- Updated Dapper reference nuget from upstream