RFR: 7081: Update Copyright year to 2021, Validate and update license attributes [v3]

[Guru Hb]

> Updated Copyright year to 2021 for below 
> 1. License show in "About" dialog
> 2. Copyright year in License file 
> 3. Update site landing page 
> 4. added a helper script which can be used to update copyright year for modified git files.

Guru Hb has updated the pull request incrementally with one additional commit since the last revision:

  Updated Copyright attributes for Eclipse 4.16, Babel, D3, d3-flame-graph, d3-graphviz, removed html5-shiv

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Changes:
  - all: https://git.openjdk.java.net/jmc/pull/190/files
  - new: https://git.openjdk.java.net/jmc/pull/190/files/f6229e37..96901546

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jmc&pr=190&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jmc&pr=190&range=01-02

  Stats: 2898 lines in 1 file changed: 1722 ins; 1074 del; 102 mod
  Patch: https://git.openjdk.java.net/jmc/pull/190.diff
  Fetch: git fetch https://git.openjdk.java.net/jmc pull/190/head:pull/190

PR: https://git.openjdk.java.net/jmc/pull/190