Unified Storage: in SQL template, also handle output data, improve API, examples and docs (#87560)

* preview of work so far

* stylistic improvements

* fix linters

* remove golden tests, they may cause the system to be too rigid to changes

* remove unnecessary code for golden tests

* remove white space mangling in Execute

* also handle output data, improve API, examples and docs

* add helper methods

* fix interface

pkg/services/store/entity/sqlstash/sqltemplate/dialect_mysql.go

@@ -5,14 +5,13 @@ package sqltemplate
 // Modes see:
 //
 //	https://dev.mysql.com/doc/refman/8.4/en/sql-mode.html#sqlmode_ansi_quotes
-var MySQL mysql
+var MySQL = mysql{
+	rowLockingClauseAll: true,
+}
 
 var _ Dialect = MySQL
 
 type mysql struct {
 	standardIdent
-}
-
-func (mysql) SelectFor(s ...string) (string, error) {
-	return rowLockingClauseAll(true).SelectFor(s...)
+	rowLockingClauseAll
 }