Measure performance improvement by "fast double writing"

[cowtowncoder]

(note: similar to #970)

Jackson 2.14 added StreamReadFeature.USE_FAST_DOUBLE_WRITER and backing implementation to speed up encoding of floating-point values from JSON (see #749). But we haven't published results (or actually done much in way of measurements).
Let's change that.

Tests to be added to /~https://github.com/FasterXML/jackson-benchmarks/

[cowtowncoder]

Interestingly enough we seem to get +20% throughput improvement with JDK 8:

java -Xmx256m -jar target/perf.jar ".*Json.*StdWriteVanilla.writeCurrencyPojo.*" -wi 3 -w 1 -i 5 -r 1 -f 5

Benchmark                                      Mode  Cnt      Score     Error  Units
JsonStdWriteVanilla.writeCurrencyPojoDefault  thrpt   25  56956.808 ± 692.258  ops/s
JsonStdWriteVanilla.writeCurrencyPojoFast     thrpt   25  67980.186 ± 431.886  ops/s

and with JDK 17 slightly more (+25 - 30%)

Benchmark                                      Mode  Cnt      Score      Error  Units
JsonStdWriteVanilla.writeCurrencyPojoDefault  thrpt   25  55172.044 ±  434.920  ops/s
JsonStdWriteVanilla.writeCurrencyPojoFast     thrpt   25  69496.599 ± 1300.986  ops/s

[cowtowncoder]

/cc @pjfanning This wrt discussions on including code. Interestingly enough relatively speed up on writing is bigger than reading for this data set. So it seems like valuable thing to have.

[cowtowncoder]

Will need to find time to blog about the results. Another interesting thing: CBOR backend is about 50% faster than Smile for this case; and about 500% speed of JSON writer. So floating-point handling efficiency matters A LOT on writing.

[cowtowncoder]

Wrote a blog post about results:

https://cowtowncoder.medium.com/jackson-2-15-faster-floating-point-writes-too-19958e310185