Update the InfuraProvider and BrowserProvider tutorial for ethers v6

[aproskill81]

Description

This PR updates the use-ethers.js-infuraprovider-or-web3provider tutorial to use ethers v6 syntax.

The tutorial currently tells users to install ethers without pinning an older version, which resolves to the latest release. However, the examples on the page still use legacy ethers v5 APIs. As a result, users following the tutorial as written can run into runtime errors when they copy the sample code.

This change aligns the tutorial with the current ethers package by updating the examples and terminology to ethers v6 and by keeping the complete sample consistent with Sepolia.

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Note

Low Risk
Low risk because changes are limited to documentation/code samples, but incorrect v6 API usage could mislead readers if not verified end-to-end.

Overview
Updates the use-ethers.js-infuraprovider-or-web3provider tutorial to ethers v6 syntax and terminology, including renaming Web3Provider references to BrowserProvider throughout.

Refreshes the embedded React code snippets to v6 APIs (e.g., new ethers.BrowserProvider(...), ethers.parseEther, provider.send('eth_requestAccounts', []), and getBlockNumber() without parameters) and keeps the complete sample aligned to the Sepolia network.

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