RFR: 6757: Selector for attribute in the flame graph [v3]

[Jean-Philippe Bempel]

> Add support for aggregating flamegraph by custom attribute.
> 
> Available attributes are chosen by their content type (number or memory).
> 
> <img width="1435" alt="Screenshot 2022-04-22 at 08 35 
> 47" src="https://user-images.githubusercontent.com/4610701/164617514-34d56474-768a-4f96-8d92-5ba617aca45a.png">
> 
> <img width="1437" alt="Screenshot 2022-04-22 at 08 36 06" src="https://user-images.githubusercontent.com/4610701/164617547-c0da25a8-d5f2-4739-bbd9-d41a3dd98d02.png">
> 
> Added support on StacktraceView:
> 
> <img width="1098" alt="Screenshot 2022-05-10 at 22 20 13" src="https://user-images.githubusercontent.com/4610701/167715364-04ca6580-4389-4c21-b6da-5d7d0fcae63b.png">

Jean-Philippe Bempel has updated the pull request incrementally with one additional commit since the last revision:

  fix copyright header

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

Changes:
  - all: https://git.openjdk.org/jmc/pull/365/files
  - new: https://git.openjdk.org/jmc/pull/365/files/b2e48e13..05a33c30

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jmc&pr=365&range=02
 - incr: https://webrevs.openjdk.org/?repo=jmc&pr=365&range=01-02

  Stats: 1 line in 1 file changed: 1 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jmc/pull/365.diff
  Fetch: git fetch https://git.openjdk.org/jmc pull/365/head:pull/365

PR: https://git.openjdk.org/jmc/pull/365