alias.type creates broken type #5467
Description
alias.type copies the type, but no constructors, so if you try to do anything after aliasing your type UCM will fail :'(
Here's a transcript to demonstrate:
```unison
type AliasMe = AliasMe
```
```ucm
scratch/main> update
scratch/main> alias.type AliasMe MyAlias
```
```unison
x = 1
```
```ucm
scratch/main> update
```
Sorry, I wasn't able to perform the update:
The type MyAlias has some constructors with missing names, and
I can't perform an update in this situation.
You can use `view MyAlias` and
`alias.term <hash> MyAlias.<ConstructorName>` to give names to
each unnamed constructor, and then try the update again.