refactor: separate round off account for opening

[ruthra-kumar]

Issue:

Rounding Entries are unavoidable in high precision Sales / Purchase Invoices that post opening entries. As the default Round off account is of type Profit and Loss, such Invoices is currently not possible to be submitted.

Solution

A separate Round Off account just for opening entries could help address this issue. This account will be under Liability.

Tasks:

• [x] ~~patch to update existing companies~~
• [x] ~~add round off for all templates in verified and unverified directory~~

Alternate approach

Abandoning above approach of updating templates and creating account automatically.

System will not auto-create any accounts. Instead,

• Company master will have new account provision round_off_for_opening, which is not mandatory
• New account_type - Round Off for Opening - is introduced
• User has to manually create an account of above type and set it in company master

Internal Ref: 18968 fixes: https://github.com/frappe/erpnext/issues/42376