Added a theme and theme provider

Client/src/Utils/Theme.js

@@ -0,0 +1,18 @@
+import { createTheme } from "@mui/material";
+
+// Colors for MUI theme
+const secondaryMain = "#475467";
+const tertiaryMain = "#475467";
+
+const theme = createTheme({
+  palette: {
+    secondary: {
+      main: secondaryMain,
+    },
+    tertiary: {
+      main: tertiaryMain,
+    },
+  },
+});
+
+export default theme;