Support for Vapor 4

[PoshAlpaca]

Adds support for Vapor 4. Originally implemented by rabc. I've combined it with our custom filterGeographyDistanceWithin and sortByDistance functions.

[PoshAlpaca]

@0xTim ready for review 🎉

[0xTim]

Great work! Few comments and things that can be updated. Some other things to look at are:

• use async/await throughout the tests assuming it's available to us. Updating the manifest to 5.5 and macOS 12 will help
• we don't have any CI any more, we should set up GH actions to run the tests to make sure things work

[PoshAlpaca]

@0xTim Thanks for the feedback! Can you take a look again?

[PoshAlpaca]

Also, I was thinking to extend DatabaseSchema.DataType with static properties so that fields in migrations can be declared like so:

.field("location", .geometricPoint2D)

instead of:

.field("location", GeometricPoint2D.dataType)

What do you think?

[0xTim]

@PoshAlpaca yep I think that's a great idea to provide a cleaner API

[0xTim]

Looking great! Last couple of changes just to CI then we're good. We should have CI passing in this PR

And let's add the data type stuff as well if it's simple

[0xTim]

Looks great! Might need to tweak the on section of CI to get it to run or wait until it's merged. Happy to merge however and fix in another PR if necessary