refactor: - Make some more arrays of Link readonly

Author: claremacrae

src/Scripting/TasksFile.ts

@@ -63,7 +63,7 @@ export class TasksFile {
     /**
      * Return an array of {@link Link} all the links in the file - both in frontmatter and in the file body.
      */
-    get outlinks(): Link[] {
+    get outlinks(): Readonly<Link[]> {
         return [...this.outlinksInProperties, ...this.outlinksInBody];
     }
 

src/Task/ListItem.ts

@@ -208,7 +208,7 @@ export class ListItem {
     /**
      * Return a list of links in the task or list item's line.
      */
-    public get outlinks(): Link[] {
+    public get outlinks(): Readonly<Link[]> {
         return this.rawLinksInFileBody
             .filter((link) => link.position.start.line === this.lineNumber)
             .map((link) => LinkResolver.getInstance().resolve(link, this.file.path));