RFR: 8304915: Create jdk.internal.util.Architecture enum and apply [v8]

[Roger Riggs]

> Define an internal jdk.internal.util.Architecture enumeration and static methods to replace uses of the system property `os.arch`.
> The enumeration values are defined to match those used in the build.
> The initial values are: `X64, X86, IA64, ARM, AARCH64, RISCV64, S390X, PPC64LE`
> Note that `amd64` and `x86_64` in the build are represented by `X64`.
> The values of the system property `os.arch` is unchanged.
> 
> The API is similar to the jdk.internal.util.OperatingSystem enum created by #[12931](https://git.openjdk.org/jdk/pull/12931).
> Uses in `java.base` and a few others are included but other modules will be done in separate PRs.

Roger Riggs has updated the pull request incrementally with three additional commits since the last revision:

 - Rename OperatingSystemProps to PlatformProps.
   Refactor OperatingSystem initialization to use strings instead of integers.
 - Revised mapping mechanism of build target architecture names to enum values.
   Unrecognized values from the build are mapped to enum value "OTHER".
   Renamed PPC64LE to PPC64 to reflect only the architecture, not the endianness.
   Added an `isLittleEndian` method to return the endianness (not currently used anywhere)
 - Revert changes to jdk.accessibility AccessBridge

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/13357/files
  - new: https://git.openjdk.org/jdk/pull/13357/files/52ca4a70..53c20c77

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13357&range=07
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13357&range=06-07

  Stats: 237 lines in 10 files changed: 123 ins; 81 del; 33 mod
  Patch: https://git.openjdk.org/jdk/pull/13357.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13357/head:pull/13357

PR: https://git.openjdk.org/jdk/pull/13357