This PR adds support for importing modules from within a Juvix project
in the Juvix REPL.
The imported module is checked (parsed, arity-checked, type-checked etc)
as normal and added to the REPL session scope. Any errors during the
checking phase is reported to the user.
### Notes:
* You must load a file before using `import`. This is because the REPL
needs to know which Juvix project is active.
* You may only import modules from within the same Juvix project.
### Examples
After launching `juvix repl`:
#### `open import`
```
Stdlib.Prelude> open import Stdlib.Data.Int.Ord
Stdlib.Prelude> 1 == 1
true
```
#### `import as`
```
Stdlib.Prelude> import Stdlib.Data.Int.Ord as Int
Stdlib.Prelude> 1 Int.== 1
true
```
#### `import`then `open`
```
Stdlib.Prelude> import Stdlib.Data.Int.Ord as Int
Stdlib.Prelude> open Int
Stdlib.Prelude> 1 == 1
true
```
#### Line-terminating semicolons are ignored:
```
Stdlib.Prelude> import Stdlib.Data.Int.Ord as Int;;;;;
Stdlib.Prelude> 1 Int.== 1
true
```
* Closes https://github.com/anoma/juvix/issues/1951
---------
Co-authored-by: Jonathan Cubides <jonathan.cubides@uib.no>
