RFR: 8354724: Methods in java.io.Reader to read all characters and all lines [v22]

[Brian Burkhalter]

> Implement the requested methods and add a test thereof.

Brian Burkhalter has updated the pull request incrementally with one additional commit since the last revision:

  8354724: Replace getChars in previous commit with subSequence

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Changes:
  - all: https://git.openjdk.org/jdk/pull/24728/files
  - new: https://git.openjdk.org/jdk/pull/24728/files/04d89963..1afba6e6

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=24728&range=21
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=24728&range=20-21

  Stats: 3 lines in 1 file changed: 0 ins; 2 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/24728.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24728/head:pull/24728

PR: https://git.openjdk.org/jdk/pull/24728