RFR: 8344706: Compiler Implementation of Compact Source Files and Instance Main Methods [v5]

[Jan Lahoda]

> This is a PR that implements JEP: Compact Source Files and Instance Main Methods. Changes include:
> - `java.io.IO` moved to `java.lang.IO`, and no longer uses `System.console()` to implement the methods (thanks to @stuart-marks)
> - `java. ... .IO` is no longer automatically imported in any compilation unit
> - the feature is finalized (i.e. no longer requires `--enable-preview`)

Jan Lahoda has updated the pull request incrementally with seven additional commits since the last revision:

 - Merge remote-tracking branch 'origin/finalize-concise-source-files' into finalize-concise-source-files
 - Reverting test commit.
   
   This reverts commit 7047cf007cc7de937aa21e96125083ee92932692.
 - Fixing tests.
 - Updating copyright year.
 - Adding bug number to tests.
 - Fixing IO tests path
 - Scratch

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/24438/files
  - new: https://git.openjdk.org/jdk/pull/24438/files/05cc336e..48399888

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=24438&range=04
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=24438&range=03-04

  Stats: 53 lines in 43 files changed: 3 ins; 0 del; 50 mod
  Patch: https://git.openjdk.org/jdk/pull/24438.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24438/head:pull/24438

PR: https://git.openjdk.org/jdk/pull/24438