chore: update Polyfill from 1.32.0 to 9.7.7

[Flash0ver]

Update Polyfill from 1.32.0 to 9.7.7.

Related

• Disambiguate forwarded types when global using directives are used SimonCropp/Polyfill#454
• chore: upgrade to C# 14.0 #4857

Additional Changes

• remove now redundant Polyfill
• enable Polyfill-feature FeatureHttp for .NET Standard 2.0 and .NET Standard 2.1
• ensure Polyfill-feature FeatureMemory is not used when System.Memory is in an incompatible version

[Flash0ver]

Potential fixes for making the namespace Polyfills globally available for projects that reference src/Sentry.csproj and has it's internals made been visible to:

• add <ItemGroup><Using Include="Polyfills" /></ItemGroup> to each of these projects
• some MSBuild additions and restructuring
• via an repo-internal Source-Generator utilizing GivesAccessTo