Docs UI update

[ZYJLiu]

1. Add Tabs/Tab component

Example usage on developer-content md files:

<!-- prettier-ignore -->
<Tabs groupId="language" items={['Rust', 'Typescript', 'Java']}>
<Tab value="Rust">Rust 1</Tab>
<Tab value="Typescript">Typescript 1</Tab>
<Tab value="Java">Java</Tab>
</Tabs>

<!-- prettier-ignore -->
<Tabs groupId="language" items={['Rust', 'Typescript', 'Go']}>
<Tab value="Rust">Rust 2</Tab>
<Tab value="Typescript">Typescript 2</Tab>
<Tab value="Go">Go</Tab>
</Tabs>

<!-- prettier-ignore -->
<Tabs groupId="package-managers" items={['pnpm', 'npm', 'yarn']}>
<Tab value="pnpm">pnpm 1</Tab> 
<Tab value="npm">npm 1</Tab>
<Tab value="yarn">yarn 1</Tab> 
</Tabs>

<!-- prettier-ignore -->
<Tabs groupId="package-managers" items={['pnpm', 'npm', 'yarn']}>
<Tab value="pnpm">pnpm 2</Tab> 
<Tab value="npm">npm 2</Tab>
<Tab value="yarn">yarn 2</Tab> 
</Tabs>

2. Add Accordion/AccordionItem component

Example usage on developer-content md files:

  <Accordion>
  <AccordionItem title="Hello">

  ```ts
  console.log("hello");

```rs println!("world"); ```

3. Update docs codeblock UI with svgs icons in header
![CleanShot 2024-07-30 at 12 20 40@2x](https://github.com/user-attachments/assets/000472a2-16a4-4eef-bc25-acfeabbd957c)

4. Add lightmode color to docs components/codeblock
![CleanShot 2024-07-30 at 12 21 46@2x](https://github.com/user-attachments/assets/4644aa98-7bfd-40b9-96db-2b22b3c57adf)
![CleanShot 2024-07-30 at 12 28 20@2x](https://github.com/user-attachments/assets/1c7d9c95-dea4-417a-a918-99a28e7e2f52)
![CleanShot 2024-07-30 at 12 29 56@2x](https://github.com/user-attachments/assets/3407a69d-d956-488b-a705-8cfe9c45796d)

5. Update docs scrollbar to only appear on hover
![CleanShot 2024-07-30 at 12 31 06](https://github.com/user-attachments/assets/b39aeaf3-738f-4a98-abb5-5e1b88b8ac7d)

6. Fix doc table of content bug where "SOL" gets converted to "SO"
7. Update Table of Contents "Edit Page" and "Scroll to Top" buttons 
![CleanShot 2024-07-31 at 10 20 03](https://github.com/user-attachments/assets/35630fb9-c9e2-478e-9912-3cf9d00b6b44)

8. Add Stack Exchange to docs secondary nav
![CleanShot 2024-07-31 at 10 22 19@2x](https://github.com/user-attachments/assets/ff60d430-2cf4-4ec1-bf66-197453f21365)

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[ZYJLiu]

Please add the usage guidelines for the new components (you've already added them in the text of this PR) into CONTRIBUTING.md

will add to developer-content, since that is where the components are used

[nickfrosty]

Please add the usage guidelines for the new components (you've already added them in the text of this PR) into CONTRIBUTING.md

added tracking issue on dev content: https://github.com/solana-foundation/developer-content/issues/288