RFR: JDK-8301990: Separate Arguments::parse into two phases [v3]

[Justin King]

> Separate out some logic from `Arguments::parse` into a separate preceding phase, preprocessing. See JDK-8301990 and JDK-8299196 for more details.

Justin King has updated the pull request incrementally with one additional commit since the last revision:

  Rename PreprocessedImpl to PreprocessedArguments
  
  Signed-off-by: Justin King <jcking at google.com>

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/12458/files
  - new: https://git.openjdk.org/jdk/pull/12458/files/20895b55..b3396d36

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=12458&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12458&range=01-02

  Stats: 15 lines in 2 files changed: 1 ins; 2 del; 12 mod
  Patch: https://git.openjdk.org/jdk/pull/12458.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12458/head:pull/12458

PR: https://git.openjdk.org/jdk/pull/12458