Issue 347: Add enw_one_hot_encode_feature helper + example using parametric and nonparametric reporting together.

[seabbs]

Description

This PR closes #347.

• Added a new helper function enw_one_hot_encode_feature() for one hot encoding variables and binding them into the original data. This is useful when users want to include parts of variables in their models as binary indicators - for example giving a specific delay its own effect.
• Added a new example showcasing how to fit a model to data reported weekly with a 3 day delay until any reports are non-zero with a weekly process model and a mixture of a parametric and non-parametric reference date model.

Checklist

• My PR is based on a package issue and I have explicitly linked it.
• I have included the target issue or issues in the PR title in the for Issue(s) issue-numbers: PR title
• I have read the contribution guidelines.
• I have tested my changes locally.
• I have added or updated unit tests where necessary.
• I have updated the documentation if required.
• My code follows the established coding standards.
• I have added a news item linked to this PR.
• I have updated the package development version by one increment in both NEWS.md and the DESCRIPTION.
• I have reviewed CI checks for this PR and addressed them as far as I am able.

[codecov]

Codecov Report

Merging #348 (bcd9244) into main (8eff560) will decrease coverage by 0.10%.
Report is 8 commits behind head on main.
The diff coverage is 85.71%.

❗ Current head bcd9244 differs from pull request most recent head 18493d1. Consider uploading reports for the commit 18493d1 to get more accurate results

@@            Coverage Diff             @@
##             main     #348      +/-   ##
==========================================
- Coverage   96.93%   96.84%   -0.10%     
==========================================
  Files          15       15              
  Lines        1862     1871       +9     
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+ Hits         1805     1812       +7     
- Misses         57       59       +2     

Files	Coverage Δ
R/preprocess.R	95.67% <100.00%> (+0.01%)	⬆️
R/model-design-tools.R	97.05% <84.61%> (-2.95%)	⬇️

[seabbs]

[Self-review] This PR adds single example that showcases how to mix the parametric and non-parametric models. It also adds a feature and a helper function that is useful when building these models (I was surprised this helper wasn't more readily available in other packages tbh).

Given its low impact on the rest of the code base I am minded to merge this now as all looks as expected and then resolve any potentially issues prior to a new release?

[seabbs]

[SELF-REVIEW] Final checks prior to merging.

[github-actions]

This is how benchmark results would change (along with a 95% confidence interval in relative change) if 42310d6 is merged into main:

•   :ballot_box_with_check:day_of_week_model: 26.6s -> 25.9s [-5.42%, +0.13%]
•   :ballot_box_with_check:latent_renewal_model: 30.8s -> 30.2s [-13.18%, +9.34%]
•   :ballot_box_with_check:missingness_model: 1.32m -> 1.32m [-1.61%, +2%]
•   :ballot_box_with_check:multi_group_latent_renewal_model: 8.07s -> 7.55s [-21.26%, +8.36%]
•   :ballot_box_with_check:preprocessing: 687ms -> 687ms [-1.42%, +1.36%]
•   :ballot_box_with_check:simple_model: 6.67s -> 6.26s [-31.26%, +19.11%]
•   :ballot_box_with_check:simple_negbin_model_with_pp: 4.52s -> 5.01s [-6.49%, +28.32%]
  These benchmarks are based on package examples which are available here. Further explanation regarding interpretation and methodology can be found in the documentation of touchstone.