Removes context parameter from instruction-scoped operations (#923)

We originally had a `context.Context` for anything that might be
traced, but it turned out to be only useful for lifecycle and host functions.

For instruction-scoped aspects like memory updates, a context parameter is too
fine-grained and also invisible in practice. For example, most users will use
the compiler engine, and its memory, global or table access will never use go's
context.

Signed-off-by: Adrian Cole <adrian@tetrate.io>

internal/integration_test/fuzzcases/fuzzcases_test.go

@@ -325,7 +325,7 @@ func Test733(t *testing.T) {
 			mem := mod.Memory()
 			require.NotNil(t, mem)
 
-			v, ok := mem.ReadUint64Le(ctx, 0x80000100)
+			v, ok := mem.ReadUint64Le(0x80000100)
 			require.True(t, ok)
 			require.Equal(t, uint64(0xffffffffffffffff), v)
 		})