[SymbolReader] Make symbol server timeout configurable

[suprak]

https://github.com/microsoft/perfview/blob/766a08ca8373d273d55da8b07147e7068e4d5f58/src/TraceEvent/Symbols/SymbolReader.cs#L1143C17-L1144C33

Working with PerfView on a slower internet environment and public symbol server frequently times out and gets blocked from additional attempts to resolve, leading to broken symbols.

FindSymbolFilePath: Time 27.2141736 sec. Timeout of 25 seconds exceeded for https://msdl.microsoft.com/download/symbols. Setting as dead server

SymbolResolver could have a property on it, say ServerTimeout or something.

[brianrob]

I agree that something like this is worthwhile. At the same time, we probably ought to change the retry behavior to ensure that a failed request doesn't mark the server dead for minutes at a time. This used to be OK, but often now this is overkill, and worse, in server processes, this is just wrong.