Hard-wire external associations: 3 sections in, this one is 4/7 (#645)

* Continue rebasing.

* Wrote unit tests for external associations.

* Fix the generated SQL.

Some syntactic sugar (capitalizing the keywords), but use the 'ON' syntax on JOINs.

* whitespace fix post rebase

* We want "management.cattle.io.projects:spec.displayName" not "...spec.clusterName"

* Fix the database calls: drop the key

* Fix breakage during automatic rebase merging gone wrong.

* ws fix - NFC

* Post rebase-merge fixes

* Fix rebase-driven merge.

* Fix rebase breakage.

* go-uber v0.5.2 prefers real arg names to '<argN>'

pkg/sqlcache/db/client.go

@@ -44,6 +44,7 @@ type Client interface {
 	QueryForRows(ctx context.Context, stmt transaction.Stmt, params ...any) (*sql.Rows, error)
 	ReadObjects(rows Rows, typ reflect.Type, shouldDecrypt bool) ([]any, error)
 	ReadStrings(rows Rows) ([]string, error)
+	ReadStrings2(rows Rows) ([][]string, error)
 	ReadInt(rows Rows) (int, error)
 	Upsert(tx transaction.Client, stmt *sql.Stmt, key string, obj any, shouldEncrypt bool) error
 	CloseStmt(closable Closable) error
@@ -265,6 +266,34 @@ func (c *client) ReadStrings(rows Rows) ([]string, error) {
 	return result, nil
 }
 
+// ReadStrings2 scans the given rows into pairs of strings, and then returns the strings as a slice.
+func (c *client) ReadStrings2(rows Rows) ([][]string, error) {
+	c.connLock.RLock()
+	defer c.connLock.RUnlock()
+
+	var result [][]string
+	for rows.Next() {
+		var key1, key2 string
+		err := rows.Scan(&key1, &key2)
+		if err != nil {
+			return nil, closeRowsOnError(rows, err)
+		}
+
+		result = append(result, []string{key1, key2})
+	}
+	err := rows.Err()
+	if err != nil {
+		return nil, closeRowsOnError(rows, err)
+	}
+
+	err = rows.Close()
+	if err != nil {
+		return nil, err
+	}
+
+	return result, nil
+}
+
 // ReadInt scans the first of the given rows into a single int (eg. for COUNT() queries)
 func (c *client) ReadInt(rows Rows) (int, error) {
 	c.connLock.RLock()