[TASK] Percentile and Median for "discrete" set

Issue Description

Is your feature request related to a problem? Please describe. As PR https://github.com/idaholab/raven/pull/1289, the percentiles and median are computed using the weighted formula. The option to get the median/percentiles in a "discrete" set must be implemented (e.g. integer sets,etc).

Describe the solution you'd like Addition of a new option for considering the set as "discrete"

Describe alternatives you've considered n/a

For Change Control Board: Issue Review

This review should occur before any development is performed as a response to this issue.

[ ] 1. Is it tagged with a type: defect or task?
[ ] 2. Is it tagged with a priority: critical, normal or minor?
[ ] 3. If it will impact requirements or requirements tests, is it tagged with requirements?
[ ] 4. If it is a defect, can it cause wrong results for users? If so an email needs to be sent to the users.
[ ] 5. Is a rationale provided? (Such as explaining why the improvement is needed or why current code is wrong.)

For Change Control Board: Issue Closure

This review should occur when the issue is imminently going to be closed.

[ ] 1. If the issue is a defect, is the defect fixed?
[ ] 2. If the issue is a defect, is the defect tested for in the regression test system? (If not explain why not.)
[ ] 3. If the issue can impact users, has an email to the users group been written (the email should specify if the defect impacts stable or master)?
[ ] 4. If the issue is a defect, does it impact the latest release branch? If yes, is there any issue tagged with release (create if needed)?
[ ] 5. If the issue is being closed without a pull request, has an explanation of why it is being closed been provided?

idaholab / raven