[license] Add vscode license, referred-to in copied source code (#13506)

In various source files in the code base, code originally from the vscode
repository, was re-used. In these instances, there is a copyright header,
like below, that refers to the file containing the full license:

/*---------------------------------------------------------------------------------------------
 *  Copyright (c) Microsoft Corporation. All rights reserved.
 *  Licensed under the MIT License. See License.txt in the project root for license information.
 *--------------------------------------------------------------------------------------------*/

I think we missed adding the full license text, as is mandated by the MIT
license.

This commit adds it, renamed for clarity. I think it should still be easy to
find, and should be less likely to cause confusion about what license is the
main one, in this repository/project.

Signed-off-by: Marc Dumais <[email protected]>

Author: marcdumais-work

LICENSE-vscode.txt

@@ -0,0 +1,29 @@
+Below is the full text of vscode's MIT license, copied from the link below (it has not changed except cosmetically, since the Theia project was started):
+
+https://github.com/microsoft/vscode/blob/2dd03eaebe21473f3af6df2a229199b9aa138e97/LICENSE.txt
+
+This license covers code originally copied from the vscode repository and integrated in this project.
+
+-----
+
+MIT License
+
+Copyright (c) 2015 - present Microsoft Corporation
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.