refs: https://github.com/TryGhost/Toolbox/issues/595
We're rolling out new rules around the node assert library, the first of which is enforcing the use of assert/strict. This means we don't need to use the strict version of methods, as the standard version will work that way by default.
This caught some gotchas in our existing usage of assert where the lack of strict mode had unexpected results:
- Url matching needs to be done on `url.href` see aa58b354a4
- Null and undefined are not the same thing, there were a few cases of this being confused
- Particularly questionable changes in [PostExporter tests](c1a468744b) tracked [here](https://github.com/TryGhost/Team/issues/3505).
- A typo see eaac9c293a
Moving forward, using assert strict should help us to catch unexpected behaviour, particularly around nulls and undefineds during implementation.
- A few users had noticed they get weird content in their excerpts when using e.g. an html block with an iframe
- This use case is common for people embedding podcasts at the top of their posts
refs https://github.com/TryGhost/Toolbox/issues/363
- this shared library is standalone, and it used in various places of
Ghost core, so we can pull it out to keep it easier to reason about
- we also use the `html-to-text` dependency in another package but it's
outdated and could now switch to this new package
