[blazor-wasm] Not launching correct OS specific browser

## Issue Description ##

When specifying browser to launch using "blazorwasm" debug type, it is only respected when using the root "browser" option. It is not respected when using stanza under OS such as "windows".

## Steps to Reproduce ##

On windows, make sure Chrome is installed and set as default browser. Also make sure Edge is installed.

Edit launch.json in project using "blazorwasm" debug type, add

"browser": "edge"

Launch and confirm Edge was launched.

Stop debugging, edit launch.json:

"windows": {
"browser": "edge"
}

Launch and Chrome (default browser) is launched.

## Expected Behavior ##

Edge is launched.

## Actual Behavior ##

Chrome is launched.

## Environment information ##

**VSCode version**: 1.50.0
**C# Extension**: 1.23.3

Dotnet Information
.NET SDK (reflecting any global.json):
Version: 5.0.100-rc.2.20480.7
Commit: 53e0c8c7f9

Runtime Environment:
OS Name: Windows
OS Version: 10.0.19041
OS Platform: Windows
RID: win10-x64
Base Path: C:\Program Files\dotnet\sdk\5.0.100-rc.2.20480.7\

Host (useful for support):
Version: 5.0.0-rc.2.20475.5
Commit: c5a3f49c88

.NET SDKs installed:
3.1.402 [C:\Program Files\dotnet\sdk]
5.0.100-rc.2.20480.7 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
Microsoft.AspNetCore.App 3.1.8 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 5.0.0-rc.2.20475.17 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.NETCore.App 3.1.8 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 5.0.0-rc.2.20475.5 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.WindowsDesktop.App 3.1.8 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 5.0.0-rc.2.20475.6 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

To install additional .NET runtimes or SDKs:
https://aka.ms/dotnet-download

Visual Studio Code Extensions

|Extension|Author|Version|
|---|---|---|
|csharp|ms-dotnettools|1.23.3|
|dotnet-test-explorer|formulahendry|0.7.4|
|git-graph|mhutchie|1.26.0|
|gitlens|eamodio|10.2.2|
|html-css-class-completion|Zignd|1.19.0|
|msbuild-project-tools|tintoy|0.3.8|
|razor-plus|austincummings|0.1.4|
|remote-ssh|ms-vscode-remote|0.55.0|
|remote-ssh-edit|ms-vscode-remote|0.55.0|
|vscode-sqlite|alexcvzz|0.9.0|;