fix(postgresql): include OUT params when matching CALL signatures

[SAY-5]

Fixes #4216.

PostgreSQL CALL requires positional placeholders for OUT parameters, but Catalog.ResolveFuncCall matched the supplied arg count against Function.InArgs(), which strips OUT and TABLE modes. A procedure declared as create_todo(IN p_task text, OUT p_id int) therefore had effective arity 1, and CALL create_todo($1, NULL) (arity 2) was rejected with function create_todo(unknown, unknown) does not exist.

This patch:

• Adds Function.CallArgs(), which is identical to InArgs() but keeps OUT parameters (still excludes TABLE).
• Adds Catalog.ResolveCallStmt, sharing the existing matcher via a private resolveFuncCall(call, isCallStmt bool) helper.
• Updates the funcCallVisitor in internal/sql/validate/func_call.go to intercept *ast.CallStmt, dispatch to ResolveCallStmt, and skip the inner FuncCall walk so it isn't re-validated against the stricter IN-only path.

Plain SELECT function calls continue to use InArgs() and are unaffected.

Reproduction

A new endtoend fixture under internal/endtoend/testdata/stored_procedures_pg_out_args/postgresql/pgx/v5 mirrors the schema and queries in the issue (positional null, typed NULL::int, and sqlc.arg for the OUT slot). It fails on main with the issue's exact error and passes after the fix.

Tests

• go test ./internal/compiler/... ./internal/sql/... — pass
• go test ./internal/endtoend/... — pass (including ddl_create_procedure and sql_syntax_calling_funcs regression coverage)
• go test -race ./internal/sql/... ./internal/compiler/... — pass