Fixes #704

Changes

• Clarifies span name patterns for databases:
  • db.statement (if low-cardinality) -> db.name db.statement (order matters because ShopDb SELECT * FROM orders WHERE order_id = ? is better than SELECT * FROM orders WHERE order_id = ? ShopDb
  • <db.operation> <db.name>.<db.sql.table> -> {db.name}.{table name} {operation} if no statement (or of a high cardinality)
• Updates span names for some individual systems to follow the same pattern
  • also adds db.sql.table to mssql - at least in java it's set for everything JDBC and makes sense on mssql
• Fallback to db.system if nothing else is available

To clarify:

• case normalization (SELECT * FROM foo vs sElEcT fROm FOO)
• elastic search uses - can/should we change?
• hbase - Document HBase attributes #742
• aws dynamodb - not clear what should be used as a span name
• CouchDB - probably has other attributes, currently doing what java instrumentation does
• Redis uses db index as database name, but index looks bad in the span names

Merge requirement checklist

• CONTRIBUTING.md guidelines followed.
• Change log entry added, according to the guidelines in When to add a changelog entry.
  • If your PR does not need a change log, start the PR title with [chore]
• schema-next.yaml updated with changes to existing conventions.