RFR: add use site null checks [v10]

[Vicente Romero]

> Adding use site null checks for method invocations. They are added by default but if option: `noUseSiteNullChecks` is passed, the compiler won't generate them

Vicente Romero has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 13 commits:

 - merge with bworld
 - Apply suggestion from @vicente-romero-oracle
 - last change
 - another change
 - adding a comment
 - changes to tests
 - code changes
 - minor code changes
 - removing comments
 - adding tests
 - ... and 3 more: https://git.openjdk.org/valhalla/compare/ab1e4545...cc8582f7

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Changes: https://git.openjdk.org/valhalla/pull/1910/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1910&range=09
  Stats: 317 lines in 2 files changed: 308 ins; 0 del; 9 mod
  Patch: https://git.openjdk.org/valhalla/pull/1910.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1910/head:pull/1910

PR: https://git.openjdk.org/valhalla/pull/1910