Use EscapeUriString instead of EscapeDataString

[am11]

It seems like due to the recent change at the storage side, the escaped index component of URL is not working anymore.

Before

$ dotnet symbol --symbols mysinglefilehostapp1 --timeout 20
Downloading from http://msdl.microsoft.com/download/symbols/
ERROR: Not Found: singlefilehost.dbg - 'http://msdl.microsoft.com/download/symbols/_.debug%2Felf-buildid-sym-27997343859af70e0bfc5e50a4d1059b3513a1c4%2F_.debug'

http://msdl.microsoft.com/download/symbols/_.debug%2Felf-buildid-sym-27997343859af70e0bfc5e50a4d1059b3513a1c4%2F_.debug is returning 404.

Replacing %2F with / fixes the issue: http://msdl.microsoft.com/download/symbols/_.debug/elf-buildid-sym-27997343859af70e0bfc5e50a4d1059b3513a1c4/_.debug is valid.

After

$ dotnet symbol --symbols mysinglefilehostapp1 --timeout 20
Downloading from http://msdl.microsoft.com/download/symbols/
Writing: ./singlefilehost.dbg

To reproduce it on machine with pre-downloaded symbol, rename ~/.dotnet/symbolcache directory temporarily to force the re-download (or try it in a new VM).

Fixes dotnet/diagnostics#1978.

[hoyosjs]

Thanks for the quick patch @am11 ☺️. Let me think about this, because this codepath gets used by sos, dotnet-dump, the symbol uploader, and dotnet-symbol. I'd like to verify that it's compatible with all the versions that we have used to upload product bits. If anything, I'm suspecting the metadata store for symbols wasn't all that smart and we were just matching upload and download. I'll need to take a quick look when I can.

[mikem8361]

@hoyosjs the more I think about this the more I think using Uri.EscapeUriString is the right thing to do. It won't affect the symbol uploader. And it allow dotnet-symbol, SOS/dotnet-dump to work with those 5.0.x, etc. builds.

[mikem8361]

@am11, I put up PR #260 that fixes the problems with EscapeUriString and doesn't escape forward slashes.