Switch to using a precompiled class for the ClassWriter bench

The gains are not as big as for scala.Predef.

```
Benchmark                                                                   Mode  Cnt      Score      Error   Units
ClassWriterBenchmark.recreateClassWriter                                   thrpt   20  48570.817 ± 2100.589   ops/s
ClassWriterBenchmark.recreateClassWriter:+memory.used                      thrpt   20        ≈ 0              bytes
ClassWriterBenchmark.recreateClassWriter:·gc.alloc.rate                    thrpt   20   1399.418 ±   60.651  MB/sec
ClassWriterBenchmark.recreateClassWriter:·gc.alloc.rate.norm               thrpt   20  45392.022 ±    0.049    B/op
ClassWriterBenchmark.recreateClassWriter:·gc.churn.PS_Eden_Space           thrpt   20   1354.515 ±   66.035  MB/sec
ClassWriterBenchmark.recreateClassWriter:·gc.churn.PS_Eden_Space.norm      thrpt   20  43934.670 ±  910.390    B/op
ClassWriterBenchmark.recreateClassWriter:·gc.churn.PS_Survivor_Space       thrpt   20      0.239 ±    0.080  MB/sec
ClassWriterBenchmark.recreateClassWriter:·gc.churn.PS_Survivor_Space.norm  thrpt   20      7.696 ±    2.499    B/op
ClassWriterBenchmark.recreateClassWriter:·gc.count                         thrpt   20    275.000             counts
ClassWriterBenchmark.recreateClassWriter:·gc.time                          thrpt   20    171.000                 ms
ClassWriterBenchmark.reuseClassWriter                                      thrpt   20  53216.337 ± 1275.213   ops/s
ClassWriterBenchmark.reuseClassWriter:+memory.used                         thrpt   20        ≈ 0              bytes
ClassWriterBenchmark.reuseClassWriter:·gc.alloc.rate                       thrpt   20   1037.234 ±   24.764  MB/sec
ClassWriterBenchmark.reuseClassWriter:·gc.alloc.rate.norm                  thrpt   20  30688.021 ±    0.049    B/op
ClassWriterBenchmark.reuseClassWriter:·gc.churn.PS_Eden_Space              thrpt   20    995.349 ±   32.375  MB/sec
ClassWriterBenchmark.reuseClassWriter:·gc.churn.PS_Eden_Space.norm         thrpt   20  29453.143 ±  775.669    B/op
ClassWriterBenchmark.reuseClassWriter:·gc.churn.PS_Survivor_Space          thrpt   20      0.214 ±    0.069  MB/sec
ClassWriterBenchmark.reuseClassWriter:·gc.churn.PS_Survivor_Space.norm     thrpt   20      6.323 ±    2.010    B/op
ClassWriterBenchmark.reuseClassWriter:·gc.count                            thrpt   20    273.000             counts
ClassWriterBenchmark.reuseClassWriter:·gc.time                             thrpt   20    163.000                 ms
```
1 job for topic/buffer-reuse in 7 minutes and 29 seconds (queued for 4 seconds)
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