Build at package initialization time (if required)

[omus]

See https://github.com/JuliaTime/TimeZones.jl/pull/389#discussion_r917343619 for details. PR causes TimeZones.build to automatically be called if the desired tzdata version has not previously been built. This should:

• Result in end-users not having to ever run TimeZones.build() themselves
• Avoid having automated environments fail in scenarios where deps/build.jl was not triggered

The main concerns with this change is that it may not play nicely with PackageCompiler.jl and users may not like that artifact retrieval and some processing could occur at package initialization time.

[omus]

I've decided to keep this change out of the TimeZones.jl 1.9.0 release. This change has a decent potential for breakage and I'd like to separate this change from the switch over to using scratch spaces and the tzjfile format.

[omus]

I lost track of this PR. Was superseded by #441