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_sqlite.go

@@ -1,7 +1,9 @@
 package sqltemplate
 
 // SQLite is an implementation of Dialect for the SQLite DMBS.
-var SQLite sqlite
+var SQLite = sqlite{
+	rowLockingClauseAll: false,
+}
 
 var _ Dialect = SQLite
 
@@ -9,8 +11,5 @@ type sqlite struct {
 	// See:
 	//	https://www.sqlite.org/lang_keywords.html
 	standardIdent
-}
-
-func (sqlite) SelectFor(s ...string) (string, error) {
-	return rowLockingClauseAll(false).SelectFor(s...)
+	rowLockingClauseAll
 }