Mangle blazor.*.js files

[TanayParikh]

Summary of Improvements

Small decreases in size, but this was some pretty low hanging fruit. 😄

File	Current Size	Optimized Size
blazor.server.js	130 kb	122 kb
blazor.webassembly.js	60 kb	59 kb
blazor.webview.js	40.5 kb	39.8 kb

Before:

asset blazor.server.js 130 KiB [emitted] [minimized] [big] (name: blazor.server)
asset blazor.webassembly.js 60 KiB [emitted] [minimized] (name: blazor.webassembly)
asset blazor.webview.js 40.5 KiB [emitted] [minimized] (name: blazor.webview)
orphan modules 452 KiB [orphan] 93 modules
runtime modules 221 bytes 1 module
cacheable modules 736 KiB
  ./Boot.Server.ts + 72 modules 390 KiB [built] [code generated]
  ./Boot.WebAssembly.ts + 31 modules 200 KiB [built] [code generated]
  ./Boot.WebView.ts + 28 modules 146 KiB [built] [code generated]

After:

asset blazor.server.js 122 KiB [emitted] [minimized] [big] (name: blazor.server)
asset blazor.webassembly.js 59 KiB [emitted] [minimized] (name: blazor.webassembly)
asset blazor.webview.js 39.8 KiB [emitted] [minimized] (name: blazor.webview)
orphan modules 452 KiB [orphan] 93 modules
runtime modules 221 bytes 1 module
cacheable modules 736 KiB
  ./Boot.Server.ts + 72 modules 390 KiB [built] [code generated]
  ./Boot.WebAssembly.ts + 31 modules 200 KiB [built] [code generated]
  ./Boot.WebView.ts + 28 modules 146 KiB [built] [code generated]

Fixes: #37260

Considering holding off on the merge till Preview 7 so this change has some time to "bake" before (preview) release.

[BrennanConroy]

Should go through the classes and use _ on the private variables like

aspnetcore/src/Components/Web.JS/src/JSInitializers/JSInitializers.ts

Line 12 in 189a4ce

private afterStartedCallbacks: AfterBlazorStartedCallback[] = [];