Build/Test Tools: Remove all previously built files when running clean:files.

Cleans old JS, CSS and Webpack files from /src so they are not automatically copied to /build when running `grunt build`. Fixes errors that may be caused by copying outdated files and/or directories to /build.

Props: desrosj, isabel_brison, SergeyBiryukov, ironprogrammer, mukesh27, robinwpdeveloper, razthee007, costdev, peterwilsoncc, azaozz.

Fixes: #47749.
Built from https://develop.svn.wordpress.org/trunk@55484


git-svn-id: http://core.svn.wordpress.org/trunk@55017 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/blocks/archives/editor-rtl.css

@@ -1,3 +0,0 @@
-ul.wp-block-archives{
-  padding-right:2.5em;
-}

wp-includes/blocks/archives/editor-rtl.min.css

@@ -1 +0,0 @@
-ul.wp-block-archives{padding-right:2.5em}

wp-includes/blocks/archives/editor.css

@@ -1,3 +0,0 @@
-ul.wp-block-archives{
-  padding-left:2.5em;
-}

wp-includes/blocks/archives/editor.min.css

@@ -1 +0,0 @@
-ul.wp-block-archives{padding-left:2.5em}

wp-includes/blocks/archives/style-rtl.css

@@ -1,7 +0,0 @@
-.wp-block-archives{
-  box-sizing:border-box;
-}
-
-.wp-block-archives-dropdown label{
-  display:block;
-}

wp-includes/blocks/archives/style-rtl.min.css

@@ -1 +0,0 @@
-.wp-block-archives{box-sizing:border-box}.wp-block-archives-dropdown label{display:block}

wp-includes/blocks/archives/style.css

@@ -1,7 +0,0 @@
-.wp-block-archives{
-  box-sizing:border-box;
-}
-
-.wp-block-archives-dropdown label{
-  display:block;
-}

wp-includes/blocks/archives/style.min.css

@@ -1 +0,0 @@
-.wp-block-archives{box-sizing:border-box}.wp-block-archives-dropdown label{display:block}