Add an MSBuild property that sets DOTNET_EnableCrashReport=1 at startup

[rolfbjarne]

As the title says.

Maybe just use EnableCrashReport=true?

References:

• https://learn.microsoft.com/en-us/dotnet/core/diagnostics/collect-dumps-crash
• [runtime] Initialize the output directory for crash reports before loading CoreCLR. Fixes #25820 #25823
• Initialize the output directory for crash reports before loading coreclr. #25820

[rolfbjarne]

CC @jonathanpeppers

[rolfbjarne]

We could also just exit in xamarin_initialize_crash_report_directory if DOTNET_EnableCrashReport is not set to 1.

[rolfbjarne]

Fixed.