Robust filename parser

[kit-ty-kate]

Issue extracted from a discussion in #9 (comment)

Different implementations of diffs output different formats for the filename with spaces or special characters (such as backslashes, which are valid on Windows). For example with spaces:

• GNU diff:

  --- "a b"	2024-04-02 13:32:43.427214939 +0100
  +++ "a c"	2024-04-02 13:32:34.520202398 +0100
  @@ -1 +0,0 @@
  -test
  

• Git diff:

  diff --git a/a b b/a c
  index 039727e..e69de29 100644
  --- a/a b
  +++ b/a c
  @@ -1 +0,0 @@
  -test
  

• Busybox diff:

  --- a b
  +++ a c
  @@ -1 +0,0 @@
  -test