RFR: 8364781: Re-examine DigitList digits resizing during parsing

[Justin Lu]

This PR changes the DigitList resizing from adding increments of 100 to a doubling resizing approach. This helps with performance of larger String values during `DecimalFormat` parsing. See the comment on the associated JBS issue for further detail.

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Commit messages:
 - init

Changes: https://git.openjdk.org/jdk/pull/26705/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26705&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8364781
  Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/26705.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26705/head:pull/26705

PR: https://git.openjdk.org/jdk/pull/26705