RFR: 6872: Add butterfly/sandwich view to JMC [v2]

[Marcus Hirt]

> This PR adds a butterfly (aka sandwich) view to JMC, showing all the callers and callees for a selected method. 
> 
> <img width="2548" height="1224" alt="buttefly" src="https://github.com/user-attachments/assets/ad3d33d8-944b-49d6-be98-62444f11da93" />
> 
> Also fixes annoying spelling error.

Marcus Hirt has updated the pull request incrementally with one additional commit since the last revision:

  Spotbugs fix

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

Changes:
  - all: https://git.openjdk.org/jmc/pull/693/files
  - new: https://git.openjdk.org/jmc/pull/693/files/6d161439..0ec1a039

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jmc&pr=693&range=01
 - incr: https://webrevs.openjdk.org/?repo=jmc&pr=693&range=00-01

  Stats: 17 lines in 1 file changed: 15 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jmc/pull/693.diff
  Fetch: git fetch https://git.openjdk.org/jmc.git pull/693/head:pull/693

PR: https://git.openjdk.org/jmc/pull/693