RFR: 8368178: Add specialization of SequencedCollection methods to emptyList, singletonList and nCopies [v3]

[Tagir F. Valeev]

> Please review this small change. If you have more ideas which classes may miss specializations of SequencedCollection methods, I can add them to this PR as well.

Tagir F. Valeev has updated the pull request incrementally with two additional commits since the last revision:

 - Add SequencedCollection specialization for immutable collections
 - Fix indentation

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Changes:
  - all: https://git.openjdk.org/jdk/pull/27406/files
  - new: https://git.openjdk.org/jdk/pull/27406/files/64e7fac2..9b92c949

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27406&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27406&range=01-02

  Stats: 62 lines in 3 files changed: 55 ins; 0 del; 7 mod
  Patch: https://git.openjdk.org/jdk/pull/27406.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27406/head:pull/27406

PR: https://git.openjdk.org/jdk/pull/27406