[release/8.0] [mono][interp] Keep delegate alive during invocation #102159
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When invoking a delegate, we were overwritting the stack slot containing the delegate object reference. In the case of invoking a delegate for a dynamic method, we were running into issues when the delegate object is collected while the method is executed because the method code is also discarded.
Backport of #100832 to release/8.0-staging
Customer Impact
Invoking a delegate for a dynamic method was potentially broken in interpreter because the method could end up being collected during execution. While this bug shouldn't be a regression from .net7, it started showing up relatively recently in various test suites, maybe caused by upgrades to toolchain/system. #101831, likely #101988
Testing
Over one month of testing on our CI without any problems
Risk
Low