RFR: 8354724: BufferedReader readAllLines and readString methods [v2]

[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: Address all PR comments to now

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Changes:
  - all: https://git.openjdk.org/jdk/pull/24728/files
  - new: https://git.openjdk.org/jdk/pull/24728/files/9fd92356..b5d82665

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=24728&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=24728&range=00-01

  Stats: 40 lines in 2 files changed: 10 ins; 2 del; 28 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