add skip_number_of_accounts_in_group_trailer option(default: false)

[gzzengwei]

when doing integration for ASB from New Zealand, the BAI2 file they provide has a different version of the Group Trailer section

Field	Description	Format	Comments	Mandatory/Optional
1	Record Code	2N	Always '98'	Mandatory
2	Control Total	N	Sum of account total	Mandatory
3	Number of Records	N	Integer, total number of all records of this group	Mandatory
4	Delimiter	1A	Always '/'

Group Trailer Example

98,73097397,507,/

While the standard of current BAI2 for Group Trailer has 5 fields, there is a Number of Accounts field before the Number of Records field

Can we add a new option skip_number_of_accounts_in_group_trailer (default to false) to skp the number of accounts field in the Group Trailer section