feat: describe queryPreprocessing and inline queries in the reference guide

Description

Describe queryPreprocessing in the reference guide:

• Support queryPreprocessing in logicalRestore
• Allow using inline SQL in queryPreprocessing (available in sections logicalRestore, logicalSnapshot, physicalSnapshot)

Related issue

database-lab#407 (closed)

Examples

Checklist

• the MR description has been reviewed
• this MR contains text changes and they have been reviewed OR there are no texts changes
• this MR contains GUI/CLI changes and they have been reviewed OR there are no GUI/CLI changes
• this MR contains API changes and they have been reviewed OR there are no API changes