Update build.gradle to more closely match CC:T's

- Adds cct-javadoc fun and renables checkstyle (yay?)
 - Fixes a few javadoc and formatting issues
 - Cherry pick the docs so illuaminate doesn't complain

doc/stub/fs.lua

@@ -0,0 +1,36 @@
+---  The FS API allows you to manipulate files and the filesystem.
+--
+-- @module fs
+
+--- Returns true if a path is mounted to the parent filesystem.
+--
+-- The root filesystem "/" is considered a mount, along with disk folders and
+-- the rom folder. Other programs (such as network shares) can exstend this to
+-- make other mount types by correctly assigning their return value for getDrive.
+--
+-- @tparam string path The path to check.
+-- @treturn boolean If the path is mounted, rather than a normal file/folder.
+-- @throws If the path does not exist.
+-- @see getDrive
+-- @since 1.87.0
+function isDriveRoot(path) end
+
+--[[- Provides completion for a file or directory name, suitable for use with
+@{_G.read}.
+
+When a directory is a possible candidate for completion, two entries are
+included - one with a trailing slash (indicating that entries within this
+directory exist) and one without it (meaning this entry is an immediate
+completion candidate). `include_dirs` can be set to @{false} to only include
+those with a trailing slash.
+
+@tparam string path The path to complete.
+@tparam string location The location where paths are resolved from.
+@tparam[opt] boolean include_files When @{false}, only directories will be
+included in the returned list.
+@tparam[opt] boolean include_dirs When @{false}, "raw" directories will not be
+included in the returned list.
+@treturn { string... } A list of possible completion candidates.
+@since 1.74
+]]
+function complete(path, location, include_files, include_dirs) end