Fix terminal logger encoding & error

[nohwnd]

Description

• Use UTF8 encoding for the output that we force in vstest.console unless the user opts out.
• Don't forward unrecognized messages to the parser, instead write them as message. Otherwise any message with "error" in it will be written as error, including passed tests that say "Standard Error: "
• Allow suppressing the logger also by MSBUILDENSURESTDOUTFORTASKPROCESSES=1

This PR is updating the dotnet SDK because the new SDK is NOT forcing MSBUILDENSURESTDOUTFORTASKPROCESSES=1 when the new logger is enabled. The old SDK was forcing it, and it would always disable the new task in our tests.

Related issue

Fix dotnet/msbuild#9674
Fix #4852

[nohwnd]

dunno why this is not picking up in source build, all the published nugets have link to repo (when I look at nuget.org). Let's merge now, and figure it out later.

[nohwnd]

/azp build

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