RFR: 5700: Improve file and socket IO rule result texts [v2]

[Jean-Philippe Bempel]

> Add new information along with longest event:
>  - report the total and average pauses for the entire recording.
>  - report the sum of all IO events for that file or host of the longest event
> Add also some mock classes for IItemCollection with some mock events

Jean-Philippe Bempel has refreshed the contents of this pull request, and previous commits have been removed. The incremental views will show differences compared to the previous content of the PR. The pull request contains one new commit since the last revision:

  5700: Improve file and socket IO rule result texts
  
  Add new information along with longest event:
   - report the total and average pauses for the entire recording.
   - report the sum of all IO events for that file or host of the longest event
  Add also some mock classes for IItemCollection with some mock events

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

Changes:
  - all: https://git.openjdk.java.net/jmc/pull/138/files
  - new: https://git.openjdk.java.net/jmc/pull/138/files/05d78da5..e57be671

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jmc&pr=138&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jmc&pr=138&range=00-01

  Stats: 236 lines in 8 files changed: 231 ins; 0 del; 5 mod
  Patch: https://git.openjdk.java.net/jmc/pull/138.diff
  Fetch: git fetch https://git.openjdk.java.net/jmc pull/138/head:pull/138

PR: https://git.openjdk.java.net/jmc/pull/138