Encoding improvements

[xinchen10]

• Small encoding in array not handled in some integer types.
• Rework the encoding layer to reduce redundant code and improve performance.

Benchmark results for a few types. master	Method	Mean	Error	StdDev	Gen 0	Gen 1	Gen 2	Allocated
ArrayAmqpSymbolDecode_1M_MAA	465.639 us	6.6509 us	5.8958 us	63.4766	20.5078	-	401,352 B
ArrayAmqpSymbolDecode_1K_MAA	44.038 us	0.6980 us	0.6187 us	6.4697	0.7935	-	40,616 B
ArrayAmqpSymbolEncode_100K_MAA	855.711 us	9.8138 us	8.6997 us	-	-	-	-
ArrayAmqpSymbolEncode_1K_MAA	85.426 us	1.6848 us	2.1307 us	-	-	-	-
Bytes_Encode_MAA	63.509 us	1.0021 us	0.9374 us	-	-	-	-
Bytes_Decode_MAA	541.192 us	9.9670 us	8.8355 us	7.8125	7.8125	7.8125	1,048,602 B
ArrayInt32Encode_MAA_1M	1,284.971 us	24.7774 us	21.9646 us	-	-	-	1 B
ArrayInt32Encode_MAA_1K	1.335 us	0.0219 us	0.0183 us	-	-	-	-
ArrayInt32Decode_1M_MAA	2,764.622 us	38.2358 us	31.9286 us	31.2500	31.2500	31.2500	4,194,338 B
ArrayInt32Decode_1K_MAA	1.558 us	0.0268 us	0.0251 us	0.6561	-	-	4,120 B

After changes	Method	Mean	Error	StdDev	Gen 0	Gen 1	Gen 2	Allocated
ArrayAmqpSymbolDecode_1M_MAA	504.052 us	9.6789 us	12.5853 us	63.4766	20.5078	-	401,352 B
ArrayAmqpSymbolDecode_1K_MAA	47.470 us	0.9227 us	0.9476 us	6.4697	0.7935	-	40,616 B
ArrayAmqpSymbolEncode_100K_MAA	422.250 us	8.3635 us	7.8233 us	-	-	-	-
ArrayAmqpSymbolEncode_1K_MAA	41.042 us	0.7985 us	0.9806 us	-	-	-	-
Bytes_Encode_MAA	64.252 us	0.6440 us	0.5378 us	-	-	-	-
Bytes_Decode_MAA	590.887 us	11.8172 us	20.6968 us	7.8125	7.8125	7.8125	1,048,600 B
ArrayInt32Encode_MAA_1M	1,303.097 us	10.0692 us	7.8614 us	-	-	-	-
ArrayInt32Encode_MAA_1K	1.274 us	0.0082 us	0.0072 us	-	-	-	-
ArrayInt32Decode_1M_MAA	3,243.336 us	51.3179 us	48.0028 us	39.0625	39.0625	39.0625	4,194,328 B
ArrayInt32Decode_1K_MAA	1.885 us	0.0313 us	0.0278 us	0.6561	-	-	4,120 B

There is a very small different because now all encoding implementations call AmqpBitConverter to do the work, instead of accessing the buffer directly. This difference should not have any impact on real world uses.

[danielmarbach]

Can we get those changes also somehow back ported to a minor version? Yes, it requires new dependencies, but that would be totally fine in a minor in my viewpoint

That would be wonderful // cc @JoshLove-msft @jsquire

[xinchen10]

It depends on a previous bigger change and introduces some breaking changes last time when I looked at it. The current focus is to get a major version released from master.