Reset derived quantity objects data and t at the beginning of a simulation

[Allentro]

Proposed changes

I have implemented a fix to reset export.t and export.data at the beginning of a simulation, accompanied by a respective test. This PR resolves #728

Types of changes

• [x] Bugfix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] Code refactoring
• [ ] Documentation Update (if none of the other choices apply)
• [x] New tests

Checklist

• [x] Black formatted
• [x] Unit tests pass locally with my changes
• [x] I have added tests that prove my fix is effective or that my feature works
• [ ] I have added necessary documentation (if appropriate)

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 98.40%. Comparing base (3d6b9da) to head (f08f0b5).

Additional details and impacted files

@@           Coverage Diff            @@
##           fenicsx     #733   +/-   ##
========================================
  Coverage    98.39%   98.40%           
========================================
  Files           27       27           
  Lines         1437     1439    +2     
========================================
+ Hits          1414     1416    +2     
  Misses          23       23           

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[RemDelaporteMathurin]

Hey @Allentro what is the status of this?

[Allentro]

Hey @Allentro what is the status of this?

Hi Remi, sorry this has slipped my list. I'll get this complete tomorrow!

[RemDelaporteMathurin]

Hi @Allentro! Do you want someone else to pick up this PR?

[Allentro]

Hi @Allentro! Do you want someone else to pick up this PR?

Hi Remi,

This slipped my inbox.. I was just scrolling through my mentions and saw this. I'm happy to work on this tomorrow evening. Sorry for the delay on this.