[Feature Request]: Make Exec task support new progress messages.

### Summary

Design and implement a (limited) progress messages support in the Exec task.

### Background and Motivation

With the new progress messages API #10415, custom task authors would be able to have an improved logger experience. However, there are many builds that use the `Exec` task in order to execute some script, instead of writing a custom task. It would be beneficial to have some support for the new progress messages API for the `Exec` task users as well.

### Proposed Feature

Similar to `CustomErrorRegularExpression` and `CustomWarningRegularExpression`, add `CustomProgressRegularExpression` to the Exec task parameters to provide a detection of messages that should be forwarded through the new progress messages API.

### Alternative Designs

Up for a discussion.