Update attributes to comply with OTel spec

[joegoldman2]

Update few attributes to match the spec (https://opentelemetry.io/docs/specs/semconv/database/database-spans/ and https://opentelemetry.io/docs/specs/semconv/database/mongodb/):

• Update activity display name
• Rename db.name to db.namespace
• Rename db.mongodb.collection to db.collection.name
• Rename db.operation to db.operation.name
• Rename db.statement to db.query.text
• Exception details should be reported as event instead of tags (https://opentelemetry.io/docs/specs/semconv/exceptions/exceptions-spans/)