feat(orm)!: ordered variable length encoding for uint32 and uint64 types (#11090)

## Description

`uint64` values are used in the ORM as auto-incrementing primary keys. Always using 8 bytes for these values is a bit of a waste of space. Unfortunately, varint encoding does not support ordered prefix iteration.

This PR introduces a compact, well-ordered variable length encoding for `uint32` and `uint64` types. `fixed32` and `fixed64` integers are still encoded as 4 and 8 byte fixed-length big-endian arrays. With this, users have a choice of encoding based on what type of data they are storing. An auto-incrementing primary key should prefer the variable length `uint64` whereas a fixed precision decimal might want to use `fixed64`.

See the golden test updates to see how this reduces key lengths.

This encoding works by using the first two bits to encode the buffer length (4 possible lengths). I'm not sure if my choice of 2,4,6 and 9 bytes is the right choice of 4 lenths for `uint64` - there are many alternate choices. I could have also chosen 3 bits and allowed for 8 possible lengths, but way waste an extra bit? Input on the right design parameters would be appreciated.



---

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- [ ] confirmed `!` in the type prefix if API or client breaking change
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orm/model/ormtable/testdata/test_auto_inc.golden

@@ -1,54 +1,54 @@
-GET 03000000000000000005 
+GET 03000005 
     PK testpb.ExampleAutoIncrementTable 5 -> {"id":5}
 GET 03808002 
     SEQ testpb.ExampleAutoIncrementTable 0
-GET 03000000000000000001 
+GET 03000001 
     PK testpb.ExampleAutoIncrementTable 1 -> {"id":1}
 ORM INSERT testpb.ExampleAutoIncrementTable {"id":1,"x":"foo","y":5}
 HAS 0301666f6f
     ERR:EOF
-SET 03000000000000000001 1203666f6f1805
+SET 03000001 1203666f6f1805
     PK testpb.ExampleAutoIncrementTable 1 -> {"id":1,"x":"foo","y":5}
 SET 03808002 01
     SEQ testpb.ExampleAutoIncrementTable 1
-SET 0301666f6f 0000000000000001
+SET 0301666f6f 0001
     UNIQ testpb.ExampleAutoIncrementTable x : foo -> 1
 GET 03808002 01
     SEQ testpb.ExampleAutoIncrementTable 1
-GET 03000000000000000002 
+GET 03000002 
     PK testpb.ExampleAutoIncrementTable 2 -> {"id":2}
 ORM INSERT testpb.ExampleAutoIncrementTable {"id":2,"x":"bar","y":10}
 HAS 0301626172
     ERR:EOF
-SET 03000000000000000002 1203626172180a
+SET 03000002 1203626172180a
     PK testpb.ExampleAutoIncrementTable 2 -> {"id":2,"x":"bar","y":10}
 SET 03808002 02
     SEQ testpb.ExampleAutoIncrementTable 2
-SET 0301626172 0000000000000002
+SET 0301626172 0002
     UNIQ testpb.ExampleAutoIncrementTable x : bar -> 2
 GET 03808002 02
     SEQ testpb.ExampleAutoIncrementTable 2
 ITERATOR 0300 -> 0301
   VALID true
-  KEY 03000000000000000001 1203666f6f1805
+  KEY 03000001 1203666f6f1805
       PK testpb.ExampleAutoIncrementTable 1 -> {"id":1,"x":"foo","y":5}
   NEXT
   VALID true
-  KEY 03000000000000000002 1203626172180a
+  KEY 03000002 1203626172180a
       PK testpb.ExampleAutoIncrementTable 2 -> {"id":2,"x":"bar","y":10}
   NEXT
   VALID false
 ITERATOR 0300 -> 0301
   VALID true
-  KEY 03000000000000000001 1203666f6f1805
+  KEY 03000001 1203666f6f1805
       PK testpb.ExampleAutoIncrementTable 1 -> {"id":1,"x":"foo","y":5}
-  KEY 03000000000000000001 1203666f6f1805
+  KEY 03000001 1203666f6f1805
       PK testpb.ExampleAutoIncrementTable 1 -> {"id":1,"x":"foo","y":5}
   NEXT
   VALID true
-  KEY 03000000000000000002 1203626172180a
+  KEY 03000002 1203626172180a
       PK testpb.ExampleAutoIncrementTable 2 -> {"id":2,"x":"bar","y":10}
-  KEY 03000000000000000002 1203626172180a
+  KEY 03000002 1203626172180a
       PK testpb.ExampleAutoIncrementTable 2 -> {"id":2,"x":"bar","y":10}
   NEXT
   VALID false