Add support for missing $casts types

[miken32]

Summary

Add support for missing $casts types. decimal, encrypted:*, immutable_date, immutable_datetime, custom_datetime, and immutable_custom_datetime. Adds testing to ensure casts are handled correctly. Resolves #1257

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Checklist

• Existing tests have been adapted and/or new tests have been added
• Add a CHANGELOG.md entry
• Code style has been fixed via composer fix-style

[mfn]

This looks very solid, thank you 👍

@barryvdh IMHO good to merge!

[miken32]

@mfn I just realized I didn't branch these changes on my fork, and I have another PR to file. What's the likelihood this PR will be merged reasonably quickly so I can delete the fork? Would I be better off closing this PR and opening a new one from a branch?

[mfn]

Would I be better off closing this PR and opening a new one from a branch?

Yes please, I can't do more then pinging @barryvdh

*technically: you could already push your current master to a branch and just change the branch here; wouldn't need a new PR; but of course fine with a new PR if it's too much trouble)

[miken32]

Closed in favour of #1262

[miken32]

Unfortunately @mfn you can't change the source branch of a PR, only the destination branch. New PR is opened, thanks for your help.