[BUG] bad handling of case-sensitivity

### Configuration
- Keka version: 1.6.0
- macOS version: 11

### Describe the bug
If a tar archive has multiple files/folder with the same name, or with the same name but a different case (uppercase vs lowercase letters), then the extraction is not correct but there is no error message

### To Reproduce
1. create a tar archive with multiple files/folder with the same name or with the same letters with uppercase/lowercase variants
```
mkdir kekatest
cd kekatest
echo 1 > test
tar -cf archive.tar test
rm test
echo 2 > test
tar -rf archive.tar test
rm test
echo 3 > TEST
tar -rf archive.tar TEST
rm TEST
mkdir test
echo A > test/A
tar -rf archive.tar test
rm -r test
mkdir TEST
echo B > test/B
tar -rf archive.tar TEST
rm -r TEST

tar -tf archive.tar
```
2. extract with Keka
3. only the first file is extracted (the file `test` with the string `1`)

### Expected behavior
A warning similar to macOS's pop-up dialog box should appear
"An item named “test” already exists in this location. Do you want to replace it with the older one you’re moving?"
- Keep Both
- Stop
- Replace