attribute: add BYTESLICE type support (#7948)

Fixes #7933 

Add BYTES type to https://pkg.go.dev/go.opentelemetry.io/otel/attribute

- Introduces BYTES type and byte 
- Adds Bytes / BytesValue constructors
- Implements hashing support
- Adds base64 representation in Emit()
- Adds test coverage for constructors, hashing, and set equality

```
$ go test -run=^$ -bench=BenchmarkByteSlice
goos: linux
goarch: amd64
pkg: go.opentelemetry.io/otel/attribute
cpu: 13th Gen Intel(R) Core(TM) i7-13800H
BenchmarkByteSlice/Value-20             149529567                7.993 ns/op           0 B/op          0 allocs/op
BenchmarkByteSlice/KeyValue-20          136973736                8.768 ns/op           0 B/op          0 allocs/op
BenchmarkByteSlice/AsByteSlice-20       562915658                2.120 ns/op           0 B/op          0 allocs/op
BenchmarkByteSlice/Emit-20              29149410                40.26 ns/op           16 B/op          1 allocs/op
PASS
```

---------

Co-authored-by: Tyler Yahn <MrAlias@users.noreply.github.com>
Co-authored-by: Robert Pająk <pellared@hotmail.com>

log/keyvalue.go

@@ -428,6 +428,9 @@ func ValueFromAttribute(value attribute.Value) Value {
 			res = append(res, StringValue(v))
 		}
 		return SliceValue(res...)
+	case attribute.BYTESLICE:
+		val := value.AsByteSlice()
+		return BytesValue(val)
 	}
 	// This code should never be reached
 	// as log attributes are a superset of standard attributes.