[GNC] Cost basis adjustment

[flywire]

I do enough of these to avoid keyboard entry by stripping the data from the
annual pdf statement. eg:
* from
https://github.com/flywire/ETF-Annual-Statement/blob/main/Tax/VAS-annual-tax-statement-2018.pdf
* to
https://github.com/flywire/ETF-Annual-Statement?tab=readme-ov-file#sample-output

I dump all the cost basis adjustments into the one account but it could
easily be written to the security account.

Regards