Allow all warnings from Kestrel to be bubbled in the AppHost

[eerhardt]

See the conversation here:

          > We suppressed that because we wanted to tightly control what was being output to the console. For example if you raise it to warning you get this in the output:

@adityamandaleeka @amcasey @halter73 - would it make sense to have a setting in Kestrel that told it "I did this override intentionally, please don't emit a warning for this?" That way Aspire wouldn't need to suppress all warnings, and then opt back in case-by-case to the warnings it wants to bubble out.

Originally posted by @eerhardt in #2914 (comment)

We should follow the suggestion of clearing out the ASPNETCORE_URLS env var and continue allowing all Kestrel warnings to be bubbled up to the user. See also

• Fix dotnet watch. #1933
• Allow cert warnings to bubble out. #3212