RFR: 6967: Add Percentage Column w.r.t 'Profiling Samples' in Thread table

[Guru Hb]

Adding "Percentage" column in Thread table (JavaApplication View). which is helpful in knowing the ratio w.r.t "Profiling Samples"
JMC 5.x had the Percentage Column in "Hot threads" tab.

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Commit messages:
 - Add Percentage Column w.r.t 'Profiling Samples' in Thread table

Changes: https://git.openjdk.java.net/jmc/pull/260/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jmc&pr=260&range=00
  Issue: https://bugs.openjdk.java.net/browse/JMC-6967
  Stats: 4 lines in 1 file changed: 3 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jmc/pull/260.diff
  Fetch: git fetch https://git.openjdk.java.net/jmc pull/260/head:pull/260

PR: https://git.openjdk.java.net/jmc/pull/260