RFR: 8319117: GrowableArray: Allow for custom initializer instead of copy constructor

[Johan Sjölen]

Hi, 

When using at_put and at_put_grow you can provide a value which will be supplied to the constructor of each element. In other words, you can intialize each element through a copy constructor.

I suggest that we also provide a function equivalent where the function is provided a pointer to the memory to be initialized. This can be used for `NONCOPYABLE` classes, for example.

This is implemented using a SFINAE pattern because `nullptr` introduces ambiguity if you use static overload.

Currently running tier1-tier4.

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Commit messages:
 - Introduce functional filler

Changes: https://git.openjdk.org/jdk/pull/16409/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16409&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8319117
  Stats: 39 lines in 2 files changed: 33 ins; 0 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/16409.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16409/head:pull/16409

PR: https://git.openjdk.org/jdk/pull/16409