RFR: JDK-8293711: Factor out size parsing functions from arguments.cpp

[Thomas Stuefe]

Arguments.cpp has several size parsing functions which would be useful in other areas of the hotspot, e.g. in NMT.

It would be nice to have them factored out into utilities, to reuse the code and to unify memory size handling. Gtests would be good too.

To simplify reviews, I split the patch into two commits.

The first commit (https://github.com/openjdk/jdk/pull/10252/commits/700e77e8d1469a2fc3d6611072c4b07aa34ab8e6) contains the unchanged code move without functional changes.

The second commit (https://github.com/openjdk/jdk/pull/10252/commits/76b4f6f30cc316fd966da60ff6601f54eeb394bf) contains the functional changes I did, as well as the new gtest.

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Commit messages:
 - Actual changes + tests
 - Verbatim move, no fixes

Changes: https://git.openjdk.org/jdk/pull/10252/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10252&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8293711
  Stats: 494 lines in 6 files changed: 376 ins; 109 del; 9 mod
  Patch: https://git.openjdk.org/jdk/pull/10252.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10252/head:pull/10252

PR: https://git.openjdk.org/jdk/pull/10252