Feature: Tax Regimes are added so that different bills with different series can be printed for Different regimes such as VAT and GST

Chore: Model relationships updated to make them simpler
Chore: Bill printing majorly refactored for it

Due to the sheer depth of the changes. There can be showstoppers. Please test it carefully

bookie/src/app/product-sale-report/product-sale-report.component.ts

@@ -1,5 +1,5 @@
 import { Component, OnInit } from '@angular/core';
-import { UntypedFormBuilder, UntypedFormGroup } from '@angular/forms';
+import { FormControl, FormGroup } from '@angular/forms';
 import { ActivatedRoute, Router } from '@angular/router';
 import * as moment from 'moment';
 
@@ -18,7 +18,10 @@ import { ProductSaleReportService } from './product-sale-report.service';
 export class ProductSaleReportComponent implements OnInit {
   info: ProductSaleReport = new ProductSaleReport();
   dataSource: ProductSaleReportDataSource = new ProductSaleReportDataSource(this.info.amounts);
-  form: UntypedFormGroup;
+  form: FormGroup<{
+    startDate: FormControl<Date>;
+    finishDate: FormControl<Date>;
+  }>;
 
   /** Columns displayed in the table. Columns IDs can be added, removed, or reordered. */
   displayedColumns = ['name', 'unbilled', 'sale', 'noCharge', 'staff', 'void'];
@@ -26,15 +29,14 @@ export class ProductSaleReportComponent implements OnInit {
   constructor(
     private route: ActivatedRoute,
     private router: Router,
-    private fb: UntypedFormBuilder,
     private toCsv: ToCsvService,
     private toaster: ToasterService,
     private ser: ProductSaleReportService,
   ) {
     // Create form
-    this.form = this.fb.group({
-      startDate: '',
-      finishDate: '',
+    this.form = new FormGroup({
+      startDate: new FormControl(new Date(), { nonNullable: true }),
+      finishDate: new FormControl(new Date(), { nonNullable: true }),
     });
   }