Feat: Implement createMany and CreateManyAndReturn

[VoidClancy]

1- define hasAnyLog() for easy imports in the main client of the log package in case any log levels were configured, to avoid verbose if condition

2- define CreateManyBuilder, CreateManyAndReturnBuilder, and their associated select and omit builders,generics in the same modular style of CreateBuilder

3- define a SupportsBulkInsert() on the client dialect, to insert in bulk if the DB supports, or to fall back to a loop in a transaction if it doesn't (Sqlite), implement the function for both PG and Sqlite

4- Refactor the duplicates between create, createMany, and createManyAndReturn:
a- Consolidated all per-field insert branching logic (cuid/uuid generation, defaults, optional fields, array handling) exclusively into the generated {{Model}}InputToMap method

b- Introduced a package-level runtime helper mapToColsVals in relations_runtime.gotpl to map a model input map to structured columns and values based on a generated stable column order slice ({{Model}}ColOrder)

c- Replaced duplicate inline column mapping inside execute{{Model}}Create with calls to {{Model}}InputToMap and mapToColsVals

d- Extracted duplicate bulk SQL generation logic (column union computation, value flattening, query param binding, and dialect-specific RETURNING clauses) into a shared runtime helper buildBulkInsertSQL

e- Updated execute{{Model}}CreateMany and execute{{Model}}CreateManyAndReturn to delegate SQL construction to buildBulkInsertSQL

f- Consolidated relation check template OR-chains into a single generated hasAnyRelation() helper method on *{{Model}}Select to check relation selections cleanly

5- test createMany, and the returning count, and test createManyAndReturn that it supports select too