Hot fix validate pmf

[kaitejohnson]

This PR does two things, one which is necessary another which may be up for discussion but does appear to be necessary if we are passing in long pmfs through a config...

1. Fix the validate_pmf() function. all.equal() needs to be wrapped in isTRUE() because it returns either TRUE or a character with difference (alternatively we could use that error message here, but I like our custom one). https://www.rdocumentation.org/packages/base/versions/3.6.2/topics/all.equal
2. Adds a test so that we catch something like this next time

The up for debate thing is that:

1. Adjusting the tolerance. I loaded from the package data and passed to the config and I think passing things around leads to rounding error, so the long infection to hospital admissions delay has a difference of just above 1e-7. I think we should be a bit more flexible with this given we are setting this up for people to pass in delays via a config.

Open to other suggestions e.g. for the pipeline we could one off load the rda from the wwinference package, use the package default, or compute directly but in general I think we want the wwinference package to allow users to specify via a config a long delay so tolerance can be a bit higher IMO.

[github-actions]

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[dylanhmorris]

LGTM. Maybe make the tolerance configurable?

[dylanhmorris]

LGTM