fix: Conversion rate validation for multi-currency invoices

[deepeshgarg007]

There are some cases when the exchange rate API doesn't work and the exchange rate in multi-currency invoices is not fetched. In such cases, a multi-currency invoice is submitted with an exchange rate of 1.

There was already validation for this on Purchase Invoice, commodified it and added it on Sales Invoice as well.

[codecov]

Codecov Report

Merging #31350 (46e6c2c) into develop (ea28ed1) will increase coverage by 0.06%.
The diff coverage is 88.15%.

@@             Coverage Diff             @@
##           develop   #31350      +/-   ##
===========================================
+ Coverage    63.68%   63.75%   +0.06%     
===========================================
  Files          984      984              
  Lines        67573    67724     +151     
===========================================
+ Hits         43037    43179     +142     
- Misses       24536    24545       +9     

Impacted Files	Coverage Δ
...ounts/doctype/purchase_invoice/purchase_invoice.py	83.48% <ø> (+<0.01%)	⬆️
...xt/accounts/doctype/payment_entry/payment_entry.py	69.38% <41.66%> (+0.28%)	⬆️
...ctype/payment_ledger_entry/payment_ledger_entry.py	76.36% <73.33%> (-13.64%)	⬇️
erpnext/controllers/accounts_controller.py	85.56% <83.33%> (-0.02%)	⬇️
...e/payment_reconciliation/payment_reconciliation.py	92.51% <93.61%> (+7.71%)	⬆️
erpnext/accounts/utils.py	73.53% <97.77%> (+3.21%)	⬆️
erpnext/accounts/doctype/gl_entry/gl_entry.py	69.10% <100.00%> (-3.00%)	⬇️
...xt/accounts/doctype/journal_entry/journal_entry.py	69.08% <100.00%> (+0.13%)	⬆️
...xt/accounts/doctype/sales_invoice/sales_invoice.py	78.41% <100.00%> (+0.10%)	⬆️
erpnext/accounts/general_ledger.py	94.61% <100.00%> (+0.02%)	⬆️
... and 25 more

[deepeshgarg007]

@Mergifyio backport version-13-hotfix

[mergify]

backport version-13-hotfix

✅ Backports have been created

• #31411 fix: Conversion rate validation for multi-currency invoices (backport #31350) has been created for branch version-13-hotfix