Run fish_indent on all our fish scripts

It's now good enough to do so.

We don't allow grid-alignment:

```fish
complete -c foo -s b -l barnanana -a '(something)'
complete -c foo -s z              -a '(something)'
```

becomes

```fish
complete -c foo -s b -l barnanana -a '(something)'
complete -c foo -s z -a '(something)'
```

It's just more trouble than it is worth.

The one part I'd change:

We align and/or'd parts of an if-condition with the in-block code:

```fish
if true
   and false
    dosomething
end
```

becomes

```fish
if true
    and false
    dosomething
end
```

but it's not used terribly much and if we ever fix it we can just
reindent.

tests/checks/empty.fish

@@ -6,13 +6,23 @@ function empty
 end
 
 # functions should not preserve $status
-false; empty; echo $status
+false
+empty
+echo $status
 # CHECK: 0
-true; empty; echo $status
+true
+empty
+echo $status
 # CHECK: 0
 
 # blocks should preserve $status
-false; begin; end; echo $status
+false
+begin
+end
+echo $status
 # CHECK: 1
-true; begin; end; echo $status
+true
+begin
+end
+echo $status
 # CHECK: 0