RFR: 6507: Use GraphViz to render stack traces

[Marcus Hirt]

Still need some pruning options to not be insanely slow when having plenty of nodes, but this is a start.

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Commit messages:
 - Formatting
 - Cleanup
 - Merge pull request #1 from cimi/graphview
 - 6507: inline graphviz wasm as base64 in js
 - Moving this out for now - to be completed at another time
 - Removing another one
 - Removing unused class
 - Allow more zoom
 - Merge branch 'graphview' of https://github.com/thegreystone/jmc into graphview
 - Merge branch 'graphview' of https://github.com/thegreystone/jmc into graphview
 - ... and 19 more: https://git.openjdk.java.net/jmc/compare/b46097d5...cd31910f

Changes: https://git.openjdk.java.net/jmc/pull/162/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jmc&pr=162&range=00
  Issue: https://bugs.openjdk.java.net/browse/JMC-6507
  Stats: 1872 lines in 29 files changed: 1858 ins; 4 del; 10 mod
  Patch: https://git.openjdk.java.net/jmc/pull/162.diff
  Fetch: git fetch https://git.openjdk.java.net/jmc pull/162/head:pull/162

PR: https://git.openjdk.java.net/jmc/pull/162