Fix Oracle bulk insert schema qualification issues

[DPschichholz]

Fix Oracle bulk insert ORA-39831 when EF Core default schema is configured

• Fix double-schema qualification when EF Core default schema is configured
• Clarify table name handling comment
• Add OpenTelemetry instrumentation project and update README

Details

When HasDefaultSchema(...) is set, tableInfo.QuotedTableName becomes a SQL-quoted fully qualified identifier (e.g. "SchemaX"."TableA"). Passing this to OracleBulkCopy.DestinationTableName causes ODP.NET to double-apply the schema, producing SchemaX.SchemaX.TableA and failing with ORA-39831.

Change

• OracleBulkInsertProvider.BulkInsert: compute destinationTableName before assigning to bulkCopy.DestinationTableName:
  • Direct insert path (tableName == tableInfo.QuotedTableName): use tableInfo.TableName (plain unquoted name — ODP.NET resolves the schema itself)
  • Temp table path: use tableName unchanged

var destinationTableName = tableName == tableInfo.QuotedTableName
    ? tableInfo.TableName
    : tableName;

bulkCopy.DestinationTableName = destinationTableName;

[SebastianStehle]

I cant speak for Oracle.

But is the whole Trace stuff not part of .NET itselt? Something like ActivitySource? And where is it actually used? I don't see it. In general I am big fan of it, but I would make a seperate PR.