RFR: 8257912: Convert enum iteration to use range-based for loops

[Ioi Lam]

* For JDK 17*

Now that [range-based for loops](https://github.com/openjdk/jdk/pull/1488) are allowed by the [HotSpot Style Guide](https://github.com/openjdk/jdk/blob/52ab72127ddc3ca6575d9d58503ec39c5dff7ab1/doc/hotspot-style.md), I have converted the more verbose syntax:

for (vmIntrinsicsIterator it = vmIntrinsicsRange.begin(); it != vmIntrinsicsRange.end(); ++it) {
  vmIntrinsicID index = *it;
  nt[as_int(index)] = string;
}

to

  for (vmIntrinsicID index : EnumRange<vmIntrinsicID>{}) {
    nt[as_int(index)] = string;
  }

I also removed the "convenient" declarations such as `vmIntrinsicsRange` and `vmIntrinsicsIterator` -- these are useful only when writing a traditional for loop, and are probably confusing to everyone else.  I've left examples in enumIterator.hpp in case anyone wants to write a traditional for loop.

I also added gtest cases for using range-based for loops with `EnumRange<>`.

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

Commit messages:
 - 8257912: Convert enum iteration to use range-based for loops

Changes: https://git.openjdk.java.net/jdk/pull/1707/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1707&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8257912
  Stats: 119 lines in 10 files changed: 71 ins; 24 del; 24 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1707.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1707/head:pull/1707

PR: https://git.openjdk.java.net/jdk/pull/1707