RFR: 6832: Should allow plotting line charts for all quantities [v2]

[Aymane Harmaz]

> This PR makes sure line charts cover all the events across multiple IItemIterables, and makes it possible for linear quantities to be represented as line charts on custom pages.

Aymane Harmaz has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:

 - update copyright year in AttributeComponentConfiguration
 - implemented merge sorting of items from multiple chunks
 - 6832: Should allow plotting line charts for all quantities

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Changes:
  - all: https://git.openjdk.org/jmc/pull/688/files
  - new: https://git.openjdk.org/jmc/pull/688/files/5b5654df..4e2ff3f4

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jmc&pr=688&range=01
 - incr: https://webrevs.openjdk.org/?repo=jmc&pr=688&range=00-01

  Stats: 868 lines in 46 files changed: 489 ins; 281 del; 98 mod
  Patch: https://git.openjdk.org/jmc/pull/688.diff
  Fetch: git fetch https://git.openjdk.org/jmc.git pull/688/head:pull/688

PR: https://git.openjdk.org/jmc/pull/688