[dataquery] Fixed Import csv for Empty csv and submitting without uploading

[SKADE2303]

Brief summary of changes

1. An error is thrown for empty CSVs for both choices in the 'CSV containing list of' dropdown (Candidates and Sessions)
2. If an incorrectly formatted csv is uploaded, it is cleared from selection and not allowed to submit.
3. If user clicks on 'Submit' without uploading a csv, an error is thrown.

Testing instructions

1. Go to DQT (Beta)
2. Click on "Continue to Define Field"
3. Select any number of fields
4. Under Define Filters, click on "Import from CSV"
5. In the ‘CSV containing a list of’ dropdown:
   - First select Candidates
   - Upload an empty CSV file.
   -> An error message would be thrown and no CSV would be loaded
6. Repeat the same steps but this time:
   -Select Sessions
   -Upload an empty CSV file.
   -> An error message would be thrown and no CSV would be loaded
7. After step 4, Click on Submit without uploading any CSV. An error would be thrown notifying the user that no CSV is uploaded.

Link(s) to related issue(s)

• Resolves [dataquery] Inconsistent and Incomplete Validation in CSV Import Tool for Filters #9880

[racostas]

I tested this PR and looks good to me.

[driusan]

@SKADE2303 can you rebase this onto the 27.0-release branch?

[racostas]

Hi @driusan, I confirm @SKADE2303 properly rebased this PR. Cloud you please take a final look and merged into 27 or into a bug_fix if the case ?

Thanks !

[christinerogers]

@driusan could this be included in the next 27 bug fix release?

It's ready for your re-review (since June)