build: Use prettier for typescript

Stop ignoring .ts files in prettier and fix existing issues.

src/app/accounting/accounting-rules/one-of-the-fields-is-required.validator.ts

@@ -2,10 +2,12 @@
 import { UntypedFormGroup, ValidatorFn, ValidationErrors } from '@angular/forms';
 
 /** Validates that one of the fields for debit or credit is filled for a given accounting rule type. */
-export const oneOfTheFieldsIsRequiredValidator: ValidatorFn = (accountingRuleForm: UntypedFormGroup): ValidationErrors | null => {
+export const oneOfTheFieldsIsRequiredValidator: ValidatorFn = (
+  accountingRuleForm: UntypedFormGroup
+): ValidationErrors | null => {
   const accountToDebit = accountingRuleForm.controls.accountToDebit.value;
   const debitTags = accountingRuleForm.controls.debitTags.value;
   const accountToCredit = accountingRuleForm.controls.accountToCredit.value;
   const creditTags = accountingRuleForm.controls.creditTags.value;
-  return ((accountToDebit || debitTags) && (accountToCredit || creditTags)) ? null : { 'error': true };
+  return (accountToDebit || debitTags) && (accountToCredit || creditTags) ? null : { error: true };
 };