RFR: 8347707: Standardise the use of os::snprintf and os::snprintf_checked

[David Holmes]

TBD

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Commit messages:
 - Make os::snprintf "nodiscard" and adjust final callsites
 - Convert os::snprintf() to os::snprintf_checked() where appropriate.
 - Forbid C library snprintf
 - Change return-value using snprintf to explicit os::snprintf
 - Change raw snprintf to os::snprintf_checked, whereever truncation would not
 - Change os::snprintf_checked to be void function.
 - Mark os::vsnprintf as nodiscard and update the callsites.

Changes: https://git.openjdk.org/jdk/pull/26470/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26470&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8347707
  Stats: 197 lines in 46 files changed: 15 ins; 5 del; 177 mod
  Patch: https://git.openjdk.org/jdk/pull/26470.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26470/head:pull/26470

PR: https://git.openjdk.org/jdk/pull/26470