Refactor UnitSpecific info => AllUnitParams type union (#701)

## Description:

By using a type union we get better type safety, enforcing each unit
type have the appropriate params when initializing

## Please complete the following:

- [x] I have added screenshots for all UI updates
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced
- [x] I understand that submitting code with bugs that could have been
caught through manual testing blocks releases and new features for all
contributors

## Please put your Discord username so you can be contacted if a bug or
regression is found:
evan

---------

Co-authored-by: evan <openfrontio@gmail.com>

src/core/execution/ShellExecution.ts

@@ -24,7 +24,7 @@ export class ShellExecution implements Execution {
 
   tick(ticks: number): void {
     if (this.shell == null) {
-      this.shell = this._owner.buildUnit(UnitType.Shell, 0, this.spawn);
+      this.shell = this._owner.buildUnit(UnitType.Shell, this.spawn, {});
     }
     if (!this.shell.isActive()) {
       this.active = false;