[clang-apply-replacements] No longer deduplucates replacements from the same TU

Summary:
clang-apply-replacements currently deduplicates all diagnostic replacements. However if you get a duplicated replacement from one TU then its expected that it should not be deduplicated. This goes some way to solving [[ https://bugs.llvm.org/show_bug.cgi?id=45150 | export-fixes to yaml adds extra newlines and breaks offsets. ]]

Take this example yaml.
```
---
MainSourceFile:  '/home/nathan/test/test.cpp'
Diagnostics:
  - DiagnosticName:  readability-braces-around-statements
    DiagnosticMessage:
      Message:         statement should be inside braces
      FilePath:        '/home/nathan/test/test.cpp'
      FileOffset:      14
      Replacements:
        - FilePath:        '/home/nathan/test/test.cpp'
          Offset:          14
          Length:          0
          ReplacementText: ' {'
        - FilePath:        '/home/nathan/test/test.cpp'
          Offset:          28
          Length:          0
          ReplacementText: '

}'
  - DiagnosticName:  readability-braces-around-statements
    DiagnosticMessage:
      Message:         statement should be inside braces
      FilePath:        '/home/nathan/test/test.cpp'
      FileOffset:      20
      Replacements:
        - FilePath:        '/home/nathan/test/test.cpp'
          Offset:          20
          Length:          0
          ReplacementText: ' {'
        - FilePath:        '/home/nathan/test/test.cpp'
          Offset:          28
          Length:          0
          ReplacementText: '

}'
...```

The current behaviour is to deduplicate the text insertions at Offset 28 and only apply one of the replacements.
However as both of these replacements came from the same translation unit we can be confident they were both meant to be applied together
The new behaviour won't deduplicate the text insertion and instead insert both of the replacements.
If the duplicate replacement is found inside different translation units (from a header file change perhaps) then they will still be deduplicated as before.

Reviewers: aaron.ballman, gribozavr2, klimek, ymandel

Reviewed By: ymandel

Subscribers: ymandel, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D76054