Shrink blazor.*.js file size, SignalR Minification

[TanayParikh]

@BrennanConroy mentioned:

SignalR mangles properties with the _ prefix so the compiler can reduce property names to single or double characters in the output, but it looks like blazor consumes SignalR from source, or from a non-mangled build. Also, blazor could add the _prefix and convert any private properties to get some savings. You can do that by adding this to the optimization section of webpack.config.js

aspnetcore/src/SignalR/clients/ts/webpack.config.base.js

Line 96 in 711bdcf

regex: /^_/

This issue tracks this effort to ensure we're minifying the SignalR bits. Not sure if we'll be able to take this for 6.0 given the current stage of the release, but will dig into it once I have some time available.