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/modifiers/modifier-list/modifier-list.component.ts

@@ -1,5 +1,5 @@
 import { Component, OnInit, ViewChild } from '@angular/core';
-import { UntypedFormBuilder, UntypedFormGroup } from '@angular/forms';
+import { FormControl, FormGroup } from '@angular/forms';
 import { MatSelectChange } from '@angular/material/select';
 import { MatTable } from '@angular/material/table';
 import { ActivatedRoute, Router } from '@angular/router';
@@ -20,19 +20,18 @@ export class ModifierListComponent implements OnInit {
   filter: BehaviorSubject<string> = new BehaviorSubject('');
   data: BehaviorSubject<Modifier[]> = new BehaviorSubject<Modifier[]>([]);
   dataSource: ModifierListDataSource = new ModifierListDataSource(this.filter, this.data);
-  form: UntypedFormGroup;
+  form: FormGroup<{
+    modifierCategory: FormControl<string | null>;
+  }>;
+
   list: Modifier[] = [];
   modifierCategories: ModifierCategory[] = [];
   /** Columns displayed in the table. Columns IDs can be added, removed, or reordered. */
   displayedColumns: string[] = ['name', 'showInBill', 'price', 'isActive', 'modifierCategory'];
 
-  constructor(
-    private route: ActivatedRoute,
-    private fb: UntypedFormBuilder,
-    private router: Router,
-  ) {
-    this.form = this.fb.group({
-      modifierCategory: '',
+  constructor(private route: ActivatedRoute, private router: Router) {
+    this.form = new FormGroup({
+      modifierCategory: new FormControl<string | null>(''),
     });
     this.data.subscribe((data: Modifier[]) => {
       this.list = data;