Prettier 2: Electric Boogaloo (#6113)

# Description of Changes
When I added Prettier formatting in #6052, my aim was to use just the
default settings in Prettier. Turns out, Prettier looks _really hard_
for any config files if it's not explicitly given one, which means that
if a developer has some sort of Prettier config file lying around on
their system, Prettier might find it and use it. Also, Prettier changes
its defaults based on stuff in `.editorconfig` without any good way of
disabling that behaviour explicitly in its config file.

To solve both of these issues, I've introduced a `.prettierrc` file
which sets Prettier's defaults explicitly, and then reformatted all our
code _again_ in Prettier's actual default settings. This should achieve
the aim of #6052 and remove the possibility for it breaking on different
dev computers.

frontend/src/core/components/shared/RainbowThemeProvider.tsx

@@ -22,7 +22,9 @@ const RainbowThemeContext = createContext<RainbowThemeContextType | null>(null);
 export function useRainbowThemeContext() {
   const context = useContext(RainbowThemeContext);
   if (!context) {
-    throw new Error("useRainbowThemeContext must be used within RainbowThemeProvider");
+    throw new Error(
+      "useRainbowThemeContext must be used within RainbowThemeProvider",
+    );
   }
   return context;
 }
@@ -35,12 +37,22 @@ export function RainbowThemeProvider({ children }: RainbowThemeProviderProps) {
   const rainbowTheme = useRainbowTheme();
 
   // Determine the Mantine color scheme
-  const mantineColorScheme = rainbowTheme.themeMode === "rainbow" ? "dark" : rainbowTheme.themeMode;
+  const mantineColorScheme =
+    rainbowTheme.themeMode === "rainbow" ? "dark" : rainbowTheme.themeMode;
 
   return (
     <RainbowThemeContext.Provider value={rainbowTheme}>
-      <MantineProvider theme={mantineTheme} defaultColorScheme={mantineColorScheme} forceColorScheme={mantineColorScheme}>
-        <div className={rainbowTheme.isRainbowMode ? rainbowStyles.rainbowMode : ""} style={{ minHeight: "100vh" }}>
+      <MantineProvider
+        theme={mantineTheme}
+        defaultColorScheme={mantineColorScheme}
+        forceColorScheme={mantineColorScheme}
+      >
+        <div
+          className={
+            rainbowTheme.isRainbowMode ? rainbowStyles.rainbowMode : ""
+          }
+          style={{ minHeight: "100vh" }}
+        >
           <ToastProvider>
             <ToastPortalBinder />
             {children}