Add caching of remove underscore result

[snuyanzin]

Also brings some speed improvements for cases of methods invocations via expressions e.g.
before

Benchmark                                      Mode  Cnt     Score    Error   Units
DatafakerExpressions.numberbetweenExpression  thrpt   10  2806.942 ± 52.094  ops/ms

after

Benchmark                                      Mode  Cnt     Score     Error   Units
DatafakerExpressions.numberbetweenExpression  thrpt   10  3333.331 ± 246.507  ops/ms

test itself

    @Benchmark
    @BenchmarkMode(Mode.Throughput)
    public void numberbetweenExpression(Blackhole blackhole) {
        blackhole.consume(DATA_FAKER.expression("#{number.number_between '1','10'}"));
    }