feat: Tax included (#370)

* feat: Tax included

* Added a toggle switch in tax settings to enable the feature.
* Database migration adding tax_included field into estimates, invoices
  and recurring invoices table.
* Toggle switch to enable and store the tax_included by estimates,
  invoices and recurring invoices.
* In case of tax included enabled, total taxes will be recalculated and
  the invoices, estimates and recurring invoices total won't be sum with
  taxes.
* Apply tax included when discount_per_item/tax_per_item item is enabled.
* Custom component to show the net total when tax included is enabled.
* Update invoice and estimates pdfs with net total.

* chore: Tax included by default

A switch button inside the tax settings to enable the tax included by
default in invoices, estimates and recurring invoices.

resources/scripts/admin/stub/invoice.js

@@ -20,6 +20,7 @@ export default function () {
     sub_total: 0,
     total: 0,
     tax_per_item: null,
+    tax_included: false,
     sales_tax_type: null,
     sales_tax_address_type: null,
     discount_per_item: null,