RFR: 8329948: Remove string template feature [v4]

[Maurizio Cimadamore]

> This PR removes support for the string template feature from the Java compiler and the Java SE API, as discussed here:
> 
> https://mail.openjdk.org/pipermail/amber-spec-experts/2024-April/004106.html

Maurizio Cimadamore has updated the pull request incrementally with one additional commit since the last revision:

  Fix issues in digit classes

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/18688/files
  - new: https://git.openjdk.org/jdk/pull/18688/files/a7396ce0..51e261bd

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18688&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18688&range=02-03

  Stats: 7 lines in 2 files changed: 0 ins; 6 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/18688.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18688/head:pull/18688

PR: https://git.openjdk.org/jdk/pull/18688