Rewrite dotnet watch command line parsing

[tmat]

Instead of launching process directly in Hot Reload with Hot Reload environment variables set on the process start info, we now launch dotnet run (or any other dotnet command) with Hot Reload variables set via environment directives (i.e. dotnet [env:XYZ=...] run <remaining args>). This allows us to avoid interpreting the subcommand and most of the command line options and arguments passed to dotnet watch. We can now easily support any existing dotnet subcommand.

We have 3 kinds of options:

1. dotnet-watch specific (such as --verbose)
   These are consumed by dotnet-watch and not included in <remaining args>

2. options that dotnet-watch needs to understand but are passed through to the subcommand (e.g. --launch-profile)
   We parse these and include them in <remaining args> (if they precede the subcommand they are moved after the subcommand).

3. other options
   These are not interpreted, just included in <remaining args>.

Fixes #39020
Fixes dotnet/aspnetcore#52294
Fixes #36611
Fixes #34055
Fixes #29539
Fixes #25612

[tmat]

@WardenGnaw PTAL