add .gitattributes and fix prettier/js warnings (#3094)

see title, as discussed in
https://github.com/MichMich/MagicMirror/pull/3093

.gitattributes

@@ -0,0 +1,56 @@
+# .gitattributes snippet to force users to use same line endings for project.
+# 
+# Handle line endings automatically for files detected as text
+# and leave all files detected as binary untouched.
+* text=auto
+
+#
+# The above will handle all files NOT found below
+# https://help.github.com/articles/dealing-with-line-endings/
+# https://github.com/Danimoth/gitattributes/blob/master/Web.gitattributes
+
+
+
+# These files are text and should be normalized (Convert crlf => lf)
+*.php text
+*.css text
+*.scss text
+*.js text
+*.json text
+*.htm text
+*.html text
+*.xml text
+*.txt text
+*.ini text
+*.inc text
+*.pl text
+*.rb text
+*.py text
+*.scm text
+*.sql text
+.htaccess text
+*.sh text
+Dockerfile* text
+*.yml text
+*.yaml text
+*.md text
+*.markdown text
+
+# These files are binary and should be left untouched
+# (binary is a macro for -text -diff)
+*.png binary
+*.jpg binary
+*.jpeg binary
+*.gif binary
+*.ico binary
+*.mov binary
+*.mp4 binary
+*.mp3 binary
+*.flv binary
+*.fla binary
+*.swf binary
+*.gz binary
+*.zip binary
+*.7z binary
+*.ttf binary
+*.pyc binary