[illink] Turn on serialization discovery in .NET 7

[sbomer]

Android application type

Android for .NET (net6.0-android, etc.)

Affected platform version

.NET 7 (rc1 SDK)

Description

dotnet/linker#2929 made serialization heuristics opt-in. To preserve the .NET 6 behavior, the Xamarin SDK should opt in to the old behavior by setting <_ExtraTrimmerArgs>--enable-serialization-discovery</_ExtraTrimmerArgs>. This can be done once using an SDK with dotnet/sdk#26993 (which will be part of rc1).

Steps to Reproduce

n/a

Did you find any workaround?

No response

Relevant log output

No response

[jonpryor]

Fixed via #7255.