Add additional log messages for dotnet trace collect --dsrouter

[jonathanpeppers]

#5241 added a new --dsrouter switch to dotnet-trace.

This simplifies the workflow for mobile, but some of the log messages like this are not present when using it this way:

How to connect current dotnet-dsrouter pid=1234 with android emulator and diagnostics tooling.
Start an application on android emulator with ONE of the following environment variables set:
[Default Tracing]
DOTNET_DiagnosticPorts=10.0.2.2:9000,nosuspend,connect
[Startup Tracing]
DOTNET_DiagnosticPorts=10.0.2.2:9000,suspend,connect
Run diagnotic tool connecting application on android emulator through dotnet-dsrouter pid=1234:
dotnet-trace collect -p 1234
See https://learn.microsoft.com/dotnet/core/diagnostics/dotnet-dsrouter for additional details and examples.

The log messages about "starting an application" and $DOTNET_DiagnosticPorts would be useful for developers.

[steveisok]

/cc @lateralusX