[SecuritySolution] Update file validation because the file type is em…

…pty on windows (elastic#199791)

## Summary

Bug: On Windows, we can't select TSV files or drag them to the file
picker. This error happens because we have a validation for the file
type, and for some reason, on Windows, it is an empty string 🤡 .

I updated the file validation logic to allow empty strings for file
types and added one extra value to the acceptable types, `.tsv`. So,
when the mime type checks fail, it will accept any files with the `tsv`
extension.


I desk-tested it on Windows-edge, Windows-chrome, Mac-chrome and it
works.

### How to test it?
* ON A WINDOWS MACHINE
* Open the security solution app and navigate to the entity store page
* Drag a TSV file created on a Windows machine; the file should be
accepted
* Click on the "select file" button and select a TSV file created on a
Windows machine
* Both methods should allow you to select the file, and you should be
able to proceed with the bulk upload

#### Do I need to checkout your code and start kibana?
If you are a lazy person like me, you can test the feature using the
cloud deployment
[here](https://kibana-pr-199791.kb.us-west2.gcp.elastic-cloud.com/app/security/entity_analytics_entity_store).
You can get the login/password using Vault. The instructions are on the
latest Cloud Deployment link, or ask me for credentials.

#### What if I don't have a Windows machine?
Buy one. I am kidding. 🤡 
You can follow [this
tutorial](https://github.com/elastic/security-team/blob/main/tools/sec-eng-prod/sep-vms/README.md#setup)
to deploy it to gcloud, and connect to it using RDP.
But If you are lazy like me, you can ask me for my Windows 11 cloud
deployment credentials.

_Obs. You need an app to access the cloud deployment via RDP. The
"Windows App" can be easily downloaded from the App Store on Mac._

### Checklist

Delete any items that are not applicable to this PR.

- [x] [Unit or functional
tests](https://www.elastic.co/guide/en/kibana/master/development-tests.html)
were updated or added to match the most common scenarios
- [x] This was checked for [cross-browser
compatibility](https://www.elastic.co/support/matrix#matrix_browsers)

x-pack/plugins/security_solution/public/entity_analytics/components/asset_criticality_file_uploader/constants.ts

@@ -5,5 +5,11 @@
  * 2.0.
  */
 
-export const SUPPORTED_FILE_TYPES = ['text/csv', 'text/plain', 'text/tab-separated-values'];
+export const SUPPORTED_FILE_TYPES = [
+  'text/csv',
+  'text/plain',
+  'text/tab-separated-values',
+  '.tsv', // Useful for Windows when it can't recognise the file extension.
+  '.csv', // Useful for Windows when it can't recognise the file extension.
+];
 export const SUPPORTED_FILE_EXTENSIONS = ['CSV', 'TXT', 'TSV'];

x-pack/plugins/security_solution/public/entity_analytics/components/asset_criticality_file_uploader/hooks.test.ts

@@ -37,12 +37,13 @@ describe('useFileValidation', () => {
   test('should call onError when an error occurs', () => {
     const onErrorMock = jest.fn();
     const onCompleteMock = jest.fn();
+    const invalidFileType = 'invalid file type';
 
     const { result } = renderHook(
       () => useFileValidation({ onError: onErrorMock, onComplete: onCompleteMock }),
       { wrapper: TestProviders }
     );
-    result.current(new File([invalidLine], 'test.csv'));
+    result.current(new File([invalidLine], 'test.csv', { type: invalidFileType }));
 
     expect(onErrorMock).toHaveBeenCalled();
     expect(onCompleteMock).not.toHaveBeenCalled();

x-pack/plugins/security_solution/public/entity_analytics/components/asset_criticality_file_uploader/validations.test.ts

@@ -56,6 +56,14 @@ describe('validateFile', () => {
     expect(result.valid).toBe(true);
   });
 
+  it('should return valid if the mime type is empty (Windows)', () => {
+    const file = new File(['file content'], 'test.csv', { type: '' });
+
+    const result = validateFile(file, formatBytes);
+
+    expect(result.valid).toBe(true);
+  });
+
   it('should return an error message if the file type is invalid', () => {
     const file = new File(['file content'], 'test.txt', { type: 'invalid-type' });
 

x-pack/plugins/security_solution/public/entity_analytics/components/asset_criticality_file_uploader/validations.ts

@@ -53,7 +53,10 @@ export const validateFile = (
   file: File,
   formatBytes: (bytes: number) => string
 ): { valid: false; errorMessage: string; code: string } | { valid: true } => {
-  if (!SUPPORTED_FILE_TYPES.includes(file.type)) {
+  if (
+    file.type !== '' && // file.type might be an empty string on windows
+    !SUPPORTED_FILE_TYPES.includes(file.type)
+  ) {
     return {
       valid: false,
       code: 'unsupported_file_type',