[release/3.1] Memory Leak in Microsoft.Extensions.Caching.Memory when handling exceptions

[wtgodbe]

Resolves #3533

Backport of dotnet/runtime#42355

When an exception is thrown inside MemoryCache.GetOrCreate, we are leaking CacheEntry objects. This is because they are not being Disposed properly, and the async local CacheEntryStack is growing indefinitely.

The fix is to ensure the CacheEntry objects are disposed correctly. In order to do this, I set a flag to indicate whether the CacheEntry.Value has been set. If it hasn't, Disposing the CacheEntry won't add it to the cache.

[Tratcher]

Note dotnet/runtime#42355 still has feedback that needs to be applied.

[wtgodbe]

Note dotnet/runtime#42355 still has feedback that needs to be applied.

@Tratcher the compiler doesn't like the shorter using syntax here, might not be on a new enough version of C#

/home/vsts/work/1/s/src/Caching/Abstractions/src/MemoryCacheExtensions.cs(38,19): error CS1003: Syntax error, '(' expected [/home/vsts/work/1/s/src/Caching/Abstractions/src/Microsoft.Extensions.Caching.Abstractions.csproj]

Will apply the rest

[wtgodbe]

Feedback has been applied

[JunTaoLuo]

There has been some changes in the original PR, please make sure this PR is updated with those changes.

[wtgodbe]

There has been some changes in the original PR, please make sure this PR is updated with those changes.

Believe I now have everything except the shorter syntax for using, which the compiler in 3.1/2.1 doesn't know about