TXTExport features

[KulaginVladimir]

Proposed changes

This PR implements several minor modifications to TXTExport & TXTExports classes:

1. Based on Formatting Issues With Exporting Mobile Concentration Files in Workshop task1 #672, TXTExport was modified to accept a user-defined format for column headers in the output files.
2. Based on TXTExports & TXTExport features #675:
   • At the initialisation stage, TXTExport.times are passed to Stepsize.milestones (if they are not present) in order to ensure that data is actually exported at these times.
   • TXTExports was modified to allow users export data at all timesteps. Also, a deprication warning was added.

Types of changes

What types of changes does your code introduce to FESTIM?

• 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)
• New tests

Checklist

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

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (22ecf3e) 98.92% compared to head (7c6ca17) 98.93%.
Report is 9 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #676      +/-   ##
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+ Coverage   98.92%   98.93%   +0.01%     
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  Files          57       57              
  Lines        2130     2154      +24     
==========================================
+ Hits         2107     2131      +24     
  Misses         23       23              

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[jhdark]

This could be a good opportunity to add in filename as a parameter of the TXTExport class same as the 'XDMFExport' class, rather than just as a property. What do you think @RemDelaporteMathurin ? Even if not, the doc strings of the class should be updated to include the attributes.

[RemDelaporteMathurin]

@jhdark that's an excellent idea! We didn't have a file name initially since it was defined from the label (and we had several files per export) but now we can definitely have a file name argument!

@KulaginVladimir do you think you could add this?

[RemDelaporteMathurin]

Hi @KulaginVladimir a few comments. Also as @jhdark said maybe we could get rid of label and simply expose filename just like we do for other exports.

[RemDelaporteMathurin]

This looks great to me! Thanks @KulaginVladimir

I'll let @jhdark review this before merging since he suggested the filename property

[jhdark]

Looks good to me