refactor(js themes): add Nebular themes copies as a base

Could be removed after upgrading to Nebular 4.2

src/app/@theme/styles/theme.default.ts

@@ -1,3 +1,48 @@
+import { NbJSThemeOptions } from '@nebular/theme';
+
+const palette = {
+  primary: '#3366ff',
+  success: '#00d68f',
+  info: '#0095ff',
+  warning: '#ffaa00',
+  danger: '#ff3d71',
+};
+
+const theme = {
+  fontMain: 'Open Sans, sans-serif',
+  fontSecondary: 'Raleway, sans-serif',
+
+  bg: '#ffffff',
+  bg2: '#f7f9fc',
+  bg3: '#edf1f7',
+  bg4: '#e4e9f2',
+
+  border: '#ffffff',
+  border2: '#f7f9fc',
+  border3: '#edf1f7',
+  border4: '#e4e9f2',
+  border5: '#c5cee0',
+
+  fg: '#8f9bb3',
+  fgHeading: '#1a2138',
+  fgText: '#1a2138',
+  fgHighlight: palette.primary,
+  layoutBg: '#f7f9fc',
+  separator: '#edf1f7',
+
+  primary: palette.primary,
+  success: palette.success,
+  info: palette.info,
+  warning: palette.warning,
+  danger: palette.danger,
+
+  primaryLight: '#598bff',
+  successLight: '#2ce69b',
+  infoLight: '#42aaff',
+  warningLight: '#ffc94d',
+  dangerLight: '#ff708d',
+};
+
 export const DEFAULT_THEME = {
   name: 'default',
   base: null,
@@ -304,4 +349,4 @@ export const DEFAULT_THEME = {
       tooltipExtraCss: 'border-radius: 10px; padding: 4px 16px;',
     },
   },
-};
+} as NbJSThemeOptions;