Remove repo contents after migration

The contents of this repository have been migrated
to the `github/codeql` repository,
specifically https://github.com/github/codeql/tree/main/go.

See #741 for details.

Remove the contents of this repo, keeping only licensing and repo docs,
so that users who clone both the `codeql` and `codeql-go` repos
do not end up with conflicting source files, particularly CodeQL packs.

Author: adityasharad

.codeqlmanifest.json

@@ -1,28 +1,3 @@
 # editor and OS artifacts
 *~
 .DS_STORE
-
-# query compilation caches
-.cache
-
-# build artifacts
-build/*
-
-# qltest projects and artifacts
-ql/test/**/*.testproj
-ql/test/**/*.actual
-ql/test/**/go.sum
-
-# Java class files
-**/*.class
-
-# binaries
-tools/bin
-tools/linux64
-tools/osx64
-tools/win64
-tools/tokenizer.jar
-main
-
-# QL pack output directories
-.codeql