add a .git-blame-ignore-revs file and populate it with a few commits (#45243)

GitHub supports hiding commits from showing up in the diff view (https://docs.github.com/en/repositories/working-with-files/using-files/viewing-a-file\#ignore-commits-in-the-blame-view). This is useful to hide commits that made (automatic) style/whitespace changes that would otherwise clutter up the blame view.

Author: KristofferC

.git-blame-ignore-revs

@@ -0,0 +1,7 @@
+# .git-blame-ignore-revs
+# whitespace: end text files with single newlines
+3903fa54a638d4546ef50e56f91f0705a8ab11ef
+# whitespace: use only UNIX line endings (\n)
+e66bfa5dd32f93e76068c00ad882c1fc839c5af8
+# whitespace: replace non-breaking space => space
+100a741e7ab38c91d48cc929bb001afc8e09261f