Allow PSD uploads over 6MB

You can't currently upload PSD files over 6MB. This is because its
mimetype is `image/vnd.adobe.photoshop`. We think this is an image, and
non-GIF images have a limit of 6MB.

To fix this, we could do one of two things:

1. Add a special case for PSD files
2. Increase the size limit for unsupported image types such as this

I went with the second option.

Tested this by:

- adding automated tests
- uploading a ~9 MB PSD file
- uploading a ~1 MB PNG
- uploading a ~27 MB PNG (which worked because it's converted to a smaller JPEG)
- uploading a ~50 MB text file
- trying to upload a ~500 MB text file (which failed, as expected)

Addresses [DESKTOP-1168][].

[DESKTOP-1168]: https://signalmessenger.atlassian.net/browse/DESKTOP-1168

ts/test-node/types/Attachment_test.ts

@@ -1,4 +1,4 @@
-// Copyright 2018-2020 Signal Messenger, LLC
+// Copyright 2018-2021 Signal Messenger, LLC
 // SPDX-License-Identifier: AGPL-3.0-only
 
 import { assert } from 'chai';
@@ -9,6 +9,31 @@ import { SignalService } from '../../protobuf';
 import { stringToArrayBuffer } from '../../../js/modules/string_to_array_buffer';
 
 describe('Attachment', () => {
+  describe('getUploadSizeLimitKb', () => {
+    const { getUploadSizeLimitKb } = Attachment;
+
+    it('returns 6000 kilobytes for supported non-GIF images', () => {
+      assert.strictEqual(getUploadSizeLimitKb(MIME.IMAGE_JPEG), 6000);
+      assert.strictEqual(getUploadSizeLimitKb(MIME.IMAGE_PNG), 6000);
+      assert.strictEqual(getUploadSizeLimitKb(MIME.IMAGE_WEBP), 6000);
+    });
+
+    it('returns 25000 kilobytes for GIFs', () => {
+      assert.strictEqual(getUploadSizeLimitKb(MIME.IMAGE_GIF), 25000);
+    });
+
+    it('returns 100000 for other file types', () => {
+      assert.strictEqual(getUploadSizeLimitKb(MIME.APPLICATION_JSON), 100000);
+      assert.strictEqual(getUploadSizeLimitKb(MIME.AUDIO_AAC), 100000);
+      assert.strictEqual(getUploadSizeLimitKb(MIME.AUDIO_MP3), 100000);
+      assert.strictEqual(getUploadSizeLimitKb(MIME.VIDEO_MP4), 100000);
+      assert.strictEqual(
+        getUploadSizeLimitKb('image/vnd.adobe.photoshop' as MIME.MIMEType),
+        100000
+      );
+    });
+  });
+
   describe('getFileExtension', () => {
     it('should return file extension from content type', () => {
       const input: Attachment.Attachment = {

ts/test-node/types/MIME_test.ts

@@ -0,0 +1,19 @@
+// Copyright 2021 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import { assert } from 'chai';
+
+import * as MIME from '../../types/MIME';
+
+describe('MIME', () => {
+  describe('isGif', () => {
+    it('returns true for GIFs', () => {
+      assert.isTrue(MIME.isGif('image/gif'));
+    });
+
+    it('returns false for non-GIFs', () => {
+      assert.isFalse(MIME.isGif('image/jpeg'));
+      assert.isFalse(MIME.isGif('text/plain'));
+    });
+  });
+});