Reduce size of TypeScript Compiler snapshot (#6809)

This PR is intentionally ugly. It duplicates all of the code in cli/js2/ into
cli/tsc/  ... because it's very important that we all understand that this code
is unnecessarily duplicated in our binary. I hope this ugliness provides the
motivation to clean it up.

The typescript git submodule is removed, because it's a very large repo and
contains all sorts of stuff we don't need. Instead the necessary files are
copied directly into the deno repo. Hence +200k lines.

COMPILER_SNAPSHOT.bin size
```
master         3448139
this branch    3320972
```

Fixes #6812

1 files changed, 9 insertions, 0 deletions

diff --git a/cli/tsc/00_bootstrap_namespace.js b/cli/tsc/00_bootstrap_namespace.js
new file mode 100644
index 000000000..bccbc09c1
--- /dev/null
+++ b/cli/tsc/00_bootstrap_namespace.js
@@ -0,0 +1,9 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+
+// The only purpose of this file is to set up "globalThis.__bootstrap" namespace,
+// that is used by scripts in this directory to reference exports between
+// the files.
+
+// This namespace is removed during runtime bootstrapping process.
+
+globalThis.__bootstrap = {};