RFR: 8358533: Improve performance of java.io.Reader.readAllLines [v7]

[Brian Burkhalter]

> Replaces the implementation `readAllCharsAsString().lines().toList()` with reading into a temporary `char` array which is then processed to detect line terminators and copy non-terminating characters into strings which are added to the list.

Brian Burkhalter has updated the pull request incrementally with two additional commits since the last revision:

 - 8358533: Use a boolean instead of fragPos != -1
 - 8358533: Immediately skip LF right after CR

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/25863/files
  - new: https://git.openjdk.org/jdk/pull/25863/files/ab959dfc..d416ec79

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=25863&range=06
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=25863&range=05-06

  Stats: 23 lines in 1 file changed: 10 ins; 4 del; 9 mod
  Patch: https://git.openjdk.org/jdk/pull/25863.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25863/head:pull/25863

PR: https://git.openjdk.org/jdk/pull/25863