[Fuzzing] [buyaa-n] Add Base64Url fuzzer

[MihuBot]

Job completed in 42 minutes.

// Base64UrlFuzzer
System.Exception: Expected=Done Actual=InvalidData
   at DotnetFuzzing.Assert.<Equal>g__Throw|0_0[T](T expected, T actual) in D:\a\runtime-utils\runtime-utils\Runner\runtime\src\libraries\Fuzzing\DotnetFuzzing\Assert.cs:line 18
   at DotnetFuzzing.Assert.Equal[T](T expected, T actual) in D:\a\runtime-utils\runtime-utils\Runner\runtime\src\libraries\Fuzzing\DotnetFuzzing\Assert.cs:line 14
   at DotnetFuzzing.Fuzzers.Base64UrlFuzzer.FuzzTarget(ReadOnlySpan`1 bytes) in D:\a\runtime-utils\runtime-utils\Runner\runtime\src\libraries\Fuzzing\DotnetFuzzing\Fuzzers\Base64UrlFuzzer.cs:line 109
   at SharpFuzz.Fuzzer.LibFuzzer.Run(ReadOnlySpanAction action, Boolean ignoreExceptions)
==8932== ERROR: libFuzzer: deadly signal
NOTE: libFuzzer has rudimentary signal handlers.
      Combine libFuzzer with AddressSanitizer or similar for better crash reports.
SUMMARY: libFuzzer: deadly signal
MS: 1 CrossOver-; base unit: 122a96fbeb0d3493dcb52f34d0b7bfecbec11036
0x73,0xa,0x45,0x73,0xa,0xa,0x3d,0x3d,
s\012Es\012\012==
artifact_prefix='./'; Test unit written to Base64UrlFuzzer-artifact-2
Base64: cwpFcwoKPT0=

Artifacts:

• Base64UrlFuzzer-stack.txt (1 KB)
• Base64UrlFuzzer-input.bin (8 B)
• Base64UrlFuzzer-inputs.zip (54 KB)

[MihaZupan]

fuzz base64url -combineWith 106771 for https://github.com/dotnet/runtime/pull/106509 + https://github.com/dotnet/runtime/pull/106771

[MihuBot]

@MihaZupan

[buyaa-n]

fuzz base64url -combineWith 106771 for https://github.com/dotnet/runtime/pull/106509 + https://github.com/dotnet/runtime/pull/106771

[MihaZupan]

The bot only listens to commands in the runtime repo, I just commented that here for reference