Normalize all line endings to LF

And force shader code to always use LF endings.

Post merge, there were a number of files that crept in with CRLF endings.

Some Tint end-to-end tests take objection to CRLF endings.

CRLF endings can be detected with:

```
git grep -I --files-with-matches --perl-regexp '\r' HEAD
```

And fixed with:

```
find . -type f -exec dos2unix {} \;
```

Bug: dawn:1339
Change-Id: Iee054bafd15875de744b86e28393cd8229bd3cfa
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/86140
Kokoro-Run: Ben Clayton <bclayton@google.com>
Reviewed-by: Antonio Maiorano <amaiorano@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>

.gitattributes

@@ -1,4 +1,9 @@
-*     text=auto
-*.sh  eol=lf
-*.gn  eol=lf
-*.gni eol=lf
+*        text=auto
+*.glsl   eol=lf
+*.gn     eol=lf
+*.gni    eol=lf
+*.hlsl   eol=lf
+*.msl    eol=lf
+*.sh     eol=lf
+*.spvasm eol=lf
+*.wgsl   eol=lf