Preserve trailing comments on specifiers (#80)

Fixes #79

Trailing comments on specifiers don't get automatically saved like
top-level ones do. This ensures that such comments are not lost

Before:
```ts
import {
    b2,a2,
    // @ts-expect-error
} from "b";

import {
    b1,
    a1,

    // @ts-expect-error
} from "a";
```
After
```ts
import {
    a1,
    b1,
    // @ts-expect-error
} from "a";
import {
    a2,
    b2,
    // @ts-expect-error
} from "b";
```

---------

Co-authored-by: Ian VanSchooten <ian.vanschooten@gmail.com>

src/utils/get-comment-registry.ts

@@ -431,6 +431,14 @@ export function attachCommentsToOutputNodes(
                 ];
 
             ownerNode = lastSpecifier;
+
+            // Start the comment on the line below the owner, to avoid gaps
+            if (
+                comment.loc?.start.line !== undefined &&
+                ownerNode.loc?.end.line
+            ) {
+                comment.loc.start.line = ownerNode.loc?.end.line + 1;
+            }
         }
 
         if (!ownerNode) {

tests/ImportCommentsPreserved/__snapshots__/ppsi.spec.ts.snap

@@ -241,6 +241,12 @@ import {
     /* @ts-expect-error*/
 } from "c";
 
+import {
+    b4,
+    a4,
+    // @ts-expect-error
+} from "c2";
+
 import {
     b2,a2,
     // @ts-expect-error
@@ -256,7 +262,6 @@ import {
 import {
     a1,
     b1,
-
     // @ts-expect-error
 } from "a";
 import {
@@ -265,5 +270,10 @@ import {
     // @ts-expect-error
 } from "b";
 import { a3, b3 } from /* @ts-expect-error*/ "c";
+import {
+    a4,
+    b4,
+    // @ts-expect-error
+} from "c2";
 
 `;

tests/ImportCommentsPreserved/import-comments-trailing-specifier-comment-lost.ts

@@ -4,6 +4,12 @@ import {
     /* @ts-expect-error*/
 } from "c";
 
+import {
+    b4,
+    a4,
+    // @ts-expect-error
+} from "c2";
+
 import {
     b2,a2,
     // @ts-expect-error