Upgrade Kotlin, Kotest, `ktlint` and Jacoco (#1331)

This commit upgrades:

* Kotlin to 1.6.20,
* Kotest to 5.2.3,
* Ktlint to 0.45.2; and
* Jacoco to 0.8.8.

Perhaps the only noteworthy change is that Ktlint now has a lint to
detect that the name of a class/object defined solely in a file has to
coincide with the filename.