Added errorbars to the plots in the fitting report

[RabiyaF]

Description of work

Fixes #1245

Testing Instructions

1. Run fitbenchmarking from the cli. Once benchmarking is complete, navigate to the fitting report pages and verify error bars are present in the plots.
2. Run pytest fitbenchmarking/results_processing/tests/test_plots.py --test-type default to verify tests are passing.

Checklist

• The title is of a format appropriate for a line in future release notes.
• I have added the appropriate tags to the PR.
• My PR represents one logical piece of work.
• My PR fully fixes the issue linked. If new issues have been created, what are they?
• I have added the appropriate tests to cover code that has been added.
• I have updated the documentation in the relevant places to cover the changes.

[coveralls]

coverage: 90.682% (-0.01%) from 90.694%
when pulling 00f0168 on RabiyaF:1245-error-bars
into 0b3ea8a on fitbenchmarking:master.

[jess-farmer]

Looks good to me and works as expected!