[IMP] l10n_ch: clearer validations for bank fields and vendor bills (ISR ref)

On res.partner.bank, we check that:
- l10n_ch_postal contains a valid postal number
- l10n_ch_isr_subscription_chf contains a valid ISR subscription number
- l10n_ch_isr_subscription_eur contains a valid ISR subscription number

ISR subscriptions numbers are postal numbers but starting with 01 or 03.
Those codes are reserved to ISR issuance.

When the bank account on a Vendor Bill is detected as
an ISR Issuer, check the reference is actually an ISR.

The 27 digits ISR Reference is error prone when typed by hand
and an error at this stage would break the payment process later.

This is required to avoid batch payment error with SEPA.

We prefer using the pretty form xx-yyyyy-z of a postal account.
The Swiss users will identify it more easily.

We always want to auto fill the field l10n_ch_postal when possible from
acc_number, which includes only 2 cases of filling acc_number:

1. a 9 position postal account number
2. an IBAN from PostFinance which includes clearing 09000

Original prs: Closes #51645, #51544, #51560

closes odoo/odoo#53815

Signed-off-by: Quentin De Paoli (qdp) <qdp@openerp.com>