all: add (*testing.B).ReportAllocs() to all benchmarks (#1919)

This allows a full picture when continuous benchmarking
is added to this repository and when any changes are made
to the code in here.

Fixes #1918

entc/gen/bench_test.go

@@ -16,6 +16,7 @@ import (
 )
 
 func BenchmarkGraph_Gen(b *testing.B) {
+	b.ReportAllocs()
 	target := filepath.Join(os.TempDir(), "ent")
 	require.NoError(b, os.MkdirAll(target, os.ModePerm), "creating tmpdir")
 	defer os.RemoveAll(target)