fix: Added return value to non type-prefixed create vector function

[RCRalph]

Fixes #8944.

Added return statement to generated non type-prefixed create vector function.

Given the following schema:

namespace Example;

table NestedTable {
  value:uint64;
}

table MyTable {
  values:[NestedTable];
}

root_type MyTable;

Previously the generated code for creating values vector looked like this:

def MyTableCreateValuesVector(builder: flatbuffers.Builder, data: Iterable[Any]) -> int:
    return builder.CreateVectorOfTables(data)

def CreateValuesVector(builder: flatbuffers.Builder, data: Iterable[Any]) -> int:
    MyTableCreateValuesVector(builder, data)

The second method is missing a return statement, which means that it always returns None instead of int.
After changes, the generated code looks like this:

def MyTableCreateValuesVector(builder: flatbuffers.Builder, data: Iterable[Any]) -> int:
    return builder.CreateVectorOfTables(data)

def CreateValuesVector(builder: flatbuffers.Builder, data: Iterable[Any]) -> int:
    return MyTableCreateValuesVector(builder, data)

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