Add credit card logos to allow displaying icons based on brand (#1280)

Co-authored-by: Hinton <oscar@oscarhinton.com>

src/scss/styles.scss

@@ -55,3 +55,5 @@
 @import "./plugins";
 @import "./tables";
 @import "./toasts";
+
+@import "../../jslib/angular/src/scss/icons.scss"; // Needs to be after font-awesome

src/scss/variables.scss

@@ -1,3 +1,5 @@
+$dark-icon-themes: "theme_dark";
+
 $primary: #175ddc;
 $primary-accent: #1252a3;
 $secondary: #ced4da;