style: add .gitattributes file (angular#13086)

On windows unless otherwise specified when cloning the repo the line ending will be CRLF which will cause some tests large specs to fail

Author: alan-agius4

.gitattributes

@@ -0,0 +1,12 @@
+# Auto detect text files and perform LF normalization
+* text=auto
+
+# JS and TS files must always use LF for tools to work
+*.js eol=lf
+*.ts eol=lf
+*.json eol=lf
+*.css eol=lf
+*.scss eol=lf
+*.less eol=lf
+*.html eol=lf
+*.svg eol=lf