CanonicalResource.versionAlgorithm should be populated for all instances

[alexzautke]

FHIR-I on 2023-01-16, WGM Q3 Monday:

@lmckenzi suggested to check that the IG Publisher makes sure that for canonical resources the IG Publisher enforces that .versionAlgorithm is populated. Additionally, there should be a default value populated for all resources within one IG (the same as for .version)

[lmckenzi]

Will need to figure out what the version algorithm is for our unique brand of semantic versioning + extension. (And maybe define a specific code for it?)

We can spit out a warning if the ImplementationGuide doesn't specify a versionAlgorithm. Can also cause the versionAlgorithm to propagate in the same manner as version itself with two new parameters (one to default, one to override).