Switching to broadcasting random walk

[seabbs]

Description

Following on from #746 this PR switches to broadcasting for the random walk parameterizations. It also adds docs and tests.

Initial submission checklist

• [x] My PR is based on a package issue and I have explicitly linked it.
• [x] I have tested my changes locally (using devtools::test() and devtools::check()).
• [x] I have added or updated unit tests where necessary.
• [x] I have updated the documentation if required and rebuilt docs if yes (using devtools::document()).
• [x] I have followed the established coding standards (and checked using lintr::lint_package()).
• [x] I have added a news item linked to this PR.

After the initial Pull Request

• [x] I have reviewed Checks for this PR and addressed any issues as far as I am able.

[github-actions[bot]]

This is how benchmark results would change (along with a 95% confidence interval in relative change) if 500b11023f53964762842197d2dc53d681edc6af is merged into main:

• :heavy_check_mark:default: 41.8s -> 42.4s [-13.84%, +16.78%]
• :heavy_check_mark:no_delays: 47.8s -> 46.5s [-17.3%, +11.58%]
• :heavy_check_mark:random_walk: 10s -> 9.2s [-16.29%, +0.01%]
• :rocket:stationary: 23.3s -> 18.4s [-38.87%, -3.64%]
• :heavy_check_mark:uncertain: 1.14m -> 1.2m [-12.93%, +24.02%] Further explanation regarding interpretation and methodology can be found in the documentation.

[github-actions[bot]]

This is how benchmark results would change (along with a 95% confidence interval in relative change) if bfc5678de3807124e267405998fa4519e887ee80 is merged into main:

• :heavy_check_mark:default: 41.5s -> 44.1s [-9.2%, +21.72%]
• :rocket:no_delays: 53.9s -> 43.6s [-34.5%, -3.74%]
• :rocket:random_walk: 10.6s -> 8.85s [-30.37%, -3.05%]
• :heavy_check_mark:stationary: 22.9s -> 20.5s [-43.07%, +22.34%]
• :heavy_check_mark:uncertain: 1.16m -> 1.26m [-17.13%, +34.06%] Further explanation regarding interpretation and methodology can be found in the documentation.

[github-actions[bot]]

This is how benchmark results would change (along with a 95% confidence interval in relative change) if d94e55eedadfeaa12062d42b05a21098cb4360b7 is merged into main:

• :heavy_check_mark:default: 42.5s -> 41.4s [-24.51%, +19.32%]
• :heavy_check_mark:no_delays: 45.4s -> 48.9s [-8.07%, +23.47%]
• :heavy_check_mark:random_walk: 9.93s -> 9.54s [-16.52%, +8.61%]
• :heavy_check_mark:stationary: 23.6s -> 19.7s [-50.29%, +16.86%]
• :heavy_check_mark:uncertain: 1.19m -> 1.19m [-32.79%, +33.36%] Further explanation regarding interpretation and methodology can be found in the documentation.

[seabbs]

yes and to ideally reduce compilation and run time (which I think it does a tiny bit)

[github-actions[bot]]

This is how benchmark results would change (along with a 95% confidence interval in relative change) if 7822fe8b28dfcc2b2ec970df59d554cbde17bba3 is merged into main:

• :heavy_check_mark:default: 45.1s -> 41.8s [-24.03%, +9.1%]
• :heavy_check_mark:no_delays: 48.4s -> 50.8s [-20.71%, +30.28%]
• :rocket:random_walk: 10s -> 8.72s [-25.79%, -0.65%]
• :heavy_check_mark:stationary: 20.1s -> 20.2s [-18.99%, +20.08%]
• :heavy_check_mark:uncertain: 1.16m -> 1.06m [-17.68%, +1.32%] Further explanation regarding interpretation and methodology can be found in the documentation.

[github-actions[bot]]

This is how benchmark results would change (along with a 95% confidence interval in relative change) if 8457a9e16ab379077bc484fb29b8ea486bda491d is merged into main:

• :rocket:default: 51.6s -> 44.2s [-25.39%, -3.16%]
• :heavy_check_mark:no_delays: 52.1s -> 50.4s [-18.4%, +11.55%]
• :heavy_check_mark:random_walk: 9.89s -> 9.79s [-10.02%, +7.99%]
• :heavy_check_mark:stationary: 20.9s -> 20.3s [-14.35%, +8.79%]
• :heavy_check_mark:uncertain: 1.07m -> 1.17m [-13.96%, +33.69%] Further explanation regarding interpretation and methodology can be found in the documentation.