android: Sent-To Function not working for plain text files

## Environment

**App version:** 1.74.3+2301 (as downloaded/installed from PlayStore on 2021-03-16)
**Device information:**
- OS name and version: Android 10 QKQ1
- Manufacturer: XiaoMi
- Model: Redmi Note 9S

## Description

**Expected behavior:**

If I share a .txt file from the filemanager app with GitJournal, I would expect GitJournal to open up and use the text contents from that file in the note. (this works only if text is shared from say another notes app and shared as text, then a note gets opened and the text gets pasted, not with an actual text file that is passed as an object it seems)

**Current behavior:**
GitJournal opens up, an empty note is shown and the passed file is neither inserted as an object (like it happes with image files) nor is the text imported. It just opens to the New-Note insert mode window.

## Steps to reproduce

1. Open Android File Manager
2. Click Textfile (plaintext.txt) to checkmark it
3. Select "Sent To" and choose GitJournal