`opentelemetry-instrumentation-mysql`: expose `capture_parameters`

Part of #4787 (global db.query.parameter.<key> tracking issue).

Background

mysql builds on the dbapi base, so once the dbapi sub-issue lands it already
knows how to emit db.query.parameter.<key> correctly — but only when
capture_parameters=True. The MySQL instrumentor never exposes that option, so
users currently have no way to enable parameter capture.

psycopg2 already exposes capture_parameters and is the reference
implementation for this change.

What to do

Thread a capture_parameters option through the instrumentor, mirroring
psycopg2:

• In MySQLInstrumentor._instrument, read
  capture_parameters = kwargs.get("capture_parameters", False) and pass it to
  dbapi.wrap_connect(...).
• In MySQLInstrumentor.instrument_connection, add a capture_parameters
  parameter and pass it to dbapi.instrument_connection(...).
• Document the option in the module docstring.

No parameter-formatting logic lives here — it all comes from the dbapi base.

Acceptance criteria

• MySQLInstrumentor().instrument(capture_parameters=True) and
  instrument_connection(conn, capture_parameters=True) both enable capture.
• With capture enabled, spans carry db.query.parameter.<key> under the new
  semconv and db.statement.parameters under the old semconv (via the base).
• Default remains no parameter capture.

Tests

• Verify capture_parameters is forwarded to the dbapi layer for both
  instrument() and instrument_connection().
• Verify db.query.parameter.<key> appears under the new semconv when enabled.

Compare the psycopg2 instrumentor with MySQLInstrumentor._instrument and instrument_connection, then trace the dbapi wrapping calls and the module docstring. Add tests for forwarding capture_parameters through both entry points and verify the new and old semconv attributes while the default remains disabled.