fix: normalize line endings

Line endings are currently mixed between LF, CRLF and both! Thankfully,
git has a way to normalize this.

https://docs.github.com/en/get-started/getting-started-with-git/configuring-git-to-handle-line-endings

.gitattributes

@@ -0,0 +1,37 @@
+# Auto detect text files and perform LF normalization
+* text=auto
+
+# Java sources
+*.java          text diff=java
+*.kt            text diff=kotlin
+*.groovy        text diff=java
+*.scala         text diff=java
+*.gradle        text diff=java
+*.gradle.kts    text diff=kotlin
+
+# These files are text and should be normalized (Convert crlf => lf)
+*.css           text diff=css
+*.scss          text diff=css
+*.sass          text
+*.df            text
+*.htm           text diff=html
+*.html          text diff=html
+*.js            text
+*.jsp           text
+*.jspf          text
+*.jspx          text
+*.properties    text
+*.tld           text
+*.tag           text
+*.tagx          text
+*.xml           text
+
+# These files are binary and should be left untouched
+# (binary is a macro for -text -diff)
+*.class         binary
+*.dll           binary
+*.ear           binary
+*.jar           binary
+*.so            binary
+*.war           binary
+*.jks           binary