Deflate compression allocates max buffer size for every operation

[CrspyAu]

Setting the maxBufferSizeBytes to handle the largest expected operation also allocates that memory for the smallest.

It would be good if the buffer could expand up to the max, rather than be pre-allocated.

Re: #238

[dvsekhvalnov]

Hi @CrspyAu , i guess good point.

Probably doable via extending MemoryStream and overriding Capacity property: https://github.com/dotnet/runtime/blob/1d1bf92fcf43aa6981804dc53c5174445069c9e4/src/libraries/System.Private.CoreLib/src/System/IO/MemoryStream.cs#L252

wanna provide proof of concept PR?

[dvsekhvalnov]

v5.1.1 released to nuget.