fix: a11y issues in react-dev-overlay (#49460)

This is a part of fix of #47351

This fixes two issues #47351 mentioned.

1. Buttons must have discernible text
-
https://dequeuniversity.com/rules/axe/4.6/button-name?application=axe-puppeteer

Before:
<img width="549" alt="Screenshot 2023-05-08 at 22 37 00"
src="https://user-images.githubusercontent.com/250407/236839743-3383aea0-f59a-4f2a-9dff-f24de692a97c.png">

This PR:
<img width="447" alt="Screenshot 2023-05-08 at 22 38 50"
src="https://user-images.githubusercontent.com/250407/236839785-3b29b74e-e4db-4ff3-a87c-b69712196264.png">

You can see the accessibility name.

3. Heading levels should only increase by one
-
https://dequeuniversity.com/rules/axe/4.6/heading-order?application=axe-puppeteer

I didn't fix the following issue in this PR because it caused the change
in appearance for the overlay.
I'll fix it as another PR.

2. Elements must have sufficient color contrast
-
https://dequeuniversity.com/rules/axe/4.6/color-contrast?application=axe-puppeteer

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packages/react-dev-overlay/src/internal/components/LeftRightDialogHeader/LeftRightDialogHeader.tsx

@@ -114,6 +114,7 @@ const LeftRightDialogHeader: React.FC<LeftRightDialogHeaderProps> =
               fill="none"
               xmlns="http://www.w3.org/2000/svg"
             >
+              <title>previous</title>
               <path
                 d="M6.99996 1.16666L1.16663 6.99999L6.99996 12.8333M12.8333 6.99999H1.99996H12.8333Z"
                 stroke="currentColor"
@@ -135,6 +136,7 @@ const LeftRightDialogHeader: React.FC<LeftRightDialogHeaderProps> =
               fill="none"
               xmlns="http://www.w3.org/2000/svg"
             >
+              <title>next</title>
               <path
                 d="M6.99996 1.16666L12.8333 6.99999L6.99996 12.8333M1.16663 6.99999H12H1.16663Z"
                 stroke="currentColor"

packages/react-dev-overlay/src/internal/container/Errors.tsx

@@ -329,11 +329,12 @@ export const styles = css`
     color: var(--color-ansi-red);
   }
 
-  .nextjs-container-errors-body > h5:not(:first-child) {
+  .nextjs-container-errors-body > h2:not(:first-child) {
     margin-top: calc(var(--size-gap-double) + var(--size-gap));
   }
-  .nextjs-container-errors-body > h5 {
+  .nextjs-container-errors-body > h2 {
     margin-bottom: var(--size-gap);
+    font-size: var(--size-font-big);
   }
 
   .nextjs-toast-errors-parent {

packages/react-dev-overlay/src/internal/container/RuntimeError.tsx

@@ -40,9 +40,9 @@ const CallStackFrame: React.FC<{
 
   return (
     <div data-nextjs-call-stack-frame>
-      <h6 data-nextjs-frame-expanded={Boolean(frame.expanded)}>
+      <h3 data-nextjs-frame-expanded={Boolean(frame.expanded)}>
         {f.methodName}
-      </h6>
+      </h3>
       <div
         data-has-source={hasSource ? 'true' : undefined}
         tabIndex={hasSource ? 10 : undefined}
@@ -126,7 +126,7 @@ const RuntimeError: React.FC<RuntimeErrorProps> = function RuntimeError({
     <React.Fragment>
       {firstFrame ? (
         <React.Fragment>
-          <h5>Source</h5>
+          <h2>Source</h2>
           {leadingFrames.map((frame, index) => (
             <CallStackFrame
               key={`leading-frame-${index}-${all}`}
@@ -142,18 +142,18 @@ const RuntimeError: React.FC<RuntimeErrorProps> = function RuntimeError({
 
       {error.componentStack ? (
         <>
-          <h5>Component Stack</h5>
+          <h2>Component Stack</h2>
           {error.componentStack.map((component, index) => (
             <div key={index} data-nextjs-component-stack-frame>
-              <h6>{component}</h6>
+              <h3>{component}</h3>
             </div>
           ))}
         </>
       ) : null}
 
       {visibleCallStackFrames.length ? (
         <React.Fragment>
-          <h5>Call Stack</h5>
+          <h2>Call Stack</h2>
           {visibleCallStackFrames.map((frame, index) => (
             <CallStackFrame key={`call-stack-${index}-${all}`} frame={frame} />
           ))}
@@ -191,14 +191,15 @@ export const styles = css`
     margin-bottom: var(--size-gap-double);
   }
 
-  [data-nextjs-call-stack-frame] > h6,
-  [data-nextjs-component-stack-frame] > h6 {
+  [data-nextjs-call-stack-frame] > h3,
+  [data-nextjs-component-stack-frame] > h3 {
     margin-top: 0;
     margin-bottom: var(--size-gap);
     font-family: var(--font-stack-monospace);
+    font-size: var(--size-font);
     color: #222;
   }
-  [data-nextjs-call-stack-frame] > h6[data-nextjs-frame-expanded='false'] {
+  [data-nextjs-call-stack-frame] > h3[data-nextjs-frame-expanded='false'] {
     color: #666;
   }
   [data-nextjs-call-stack-frame] > div {