RFR: 8298352: apple.laf.JRSUIUtils class creates many indirections

[SWinxy]

`JRSUIUtils.java` structurally does things weirdly. The utility class mostly passes parameters from functions to other functions. The indirection makes things harder to understand the eventual purpose.

Take `AquaInternalFrameBorderMetrics.java`. It has a `static boolean` that caches a call to `shouldUseLegacyBorderMetrics()`, which returns `isSnowLeopardOrBelow`, itself a cached call to `isMacOSXSnowLeopardOrBelow()`, which is what finally calls `currentMacOSXVersionMatchesGivenVersionRange()`. When looking at the code, it takes time to unravel the path it takes. Instead of that, a `public static final boolean` can expose the cached value and, in doing so, exposes the *meaning* behind the check.

In `AquaLookAndFeel.java`, the value of `TabbedPaneUI` is calculated using `JRSUIUtils.TabbedPane.shouldUseTabbedPaneContrastUI()`, but that could mean any reason for why `"AquaTabbedPaneContrastUI"` may be the value as opposed to `"AquaTabbedPaneUI"`. Replacing it with `JRSUIUtils.isSnowLeopardOrBelow` reveals that it actually has to do with the OS version being, well, Snow Leopard or below.

These change makes understanding the code easier and quicker. Also more optimized.

Changes:
* add JRSUIConstants.ScrollBarPart.ordinal() to return the property's ordinal value, which is not public
* change 3 access modifiers in JRSUIControl to public allowing for access outside the package
* JRSUIConstants.NineSliceMetricsProvider changed to a normal Function<>
* cache `isMacOSXBigSurOrAbove` rather than calling it twice
* inline the functions for clarity
* change static initialization to group all version checks together
* document JRSUIUtils

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Commit messages:
 - Group OSX version getting into one static block
 - Update copyright year
 - apple.laf.JRSUIUtils does not indicate what is checked, and passes things unnecessarily

Changes: https://git.openjdk.org/jdk/pull/10326/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10326&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8298352
  Stats: 190 lines in 13 files changed: 19 ins; 89 del; 82 mod
  Patch: https://git.openjdk.org/jdk/pull/10326.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10326/head:pull/10326

PR: https://git.openjdk.org/jdk/pull/10326