RFR: JDK-8315457 Implementation of String Templates (Second Preview)

[Jim Laskey]

Update String Templates for a second preview. With the addition of

- Expression type and throws are determined from the `process` method of the processor type and not the processor type.

- Qualified `STR` and `RAW` are treated the same as unqualified `STR` and `RAW` .

- Raw (generic) process types are no longer an error.

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Commit messages:
 - Accept qualified STR and RAW
 - String Templates (second preview)

Changes: https://git.openjdk.org/jdk/pull/16202/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16202&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8315457
  Stats: 91 lines in 29 files changed: 29 ins; 30 del; 32 mod
  Patch: https://git.openjdk.org/jdk/pull/16202.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16202/head:pull/16202

PR: https://git.openjdk.org/jdk/pull/16202