[browser] Use OverrideHtmlAssetPlaceholders=true in browser template

[maraf]

• Update browserwasm template to include placeholders and MSBuild settings to enable override of HTML files during build.
• Wasm.Build.Tests now expects that dotnet.js is fingerprinted.

Contributes to dotnet/aspnetcore#60536

[Copilot]

Pull Request Overview

This PR updates the browser wasm template to support HTML overrides during build and adjusts the fingerprint expectations for specific dotnet files. Key changes include:

• Updating the fingerprint flag for "dotnet.js" and the boot config file in WasmSdkBasedProjectProvider.cs.
• Introducing a new helper method GetBootConfigPath in ProjectProviderBase.cs to locate the fingerprinted boot configuration file.

Reviewed Changes

Copilot reviewed 2 out of 12 changed files in this pull request and generated 1 comment.

File	Description
src/mono/wasm/Wasm.Build.Tests/WasmSdkBasedProjectProvider.cs	Updated boolean flags to enable fingerprinting for dotnet.js and boot config file.
src/mono/wasm/Wasm.Build.Tests/ProjectProviderBase.cs	Refactored boot config file lookup by introducing GetBootConfigPath and updating its usage.

Files not reviewed (10)

• src/mono/wasm/templates/templates/browser/browser.0.csproj: Language not supported
• src/mono/wasm/templates/templates/browser/wwwroot/index.html: Language not supported
• src/mono/wasm/testassets/BlazorBasicTestApp/App/BlazorBasicTestApp.csproj: Language not supported
• src/mono/wasm/testassets/BlazorBasicTestApp/App/wwwroot/index.html: Language not supported
• src/mono/wasm/testassets/WasmBasicTestApp/App/WasmBasicTestApp.csproj: Language not supported
• src/mono/wasm/testassets/WasmBasicTestApp/App/wwwroot/index.html: Language not supported
• src/mono/wasm/testassets/WasmOnAspNetCore/BlazorClient/BlazorClient.csproj: Language not supported
• src/mono/wasm/testassets/WasmOnAspNetCore/BlazorClient/wwwroot/index.html: Language not supported
• src/mono/wasm/testassets/WasmOnAspNetCore/WasmBrowserClient/WasmBrowserClient.csproj: Language not supported
• src/mono/wasm/testassets/WasmOnAspNetCore/WasmBrowserClient/wwwroot/index.html: Language not supported

Comments suppressed due to low confidence (1)

src/mono/wasm/Wasm.Build.Tests/ProjectProviderBase.cs:512

• The GetBootConfigPath method does not return a value. Please add an appropriate 'return bootJsonPath;' statement before the method concludes.

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