build: install typescript in Dockerfile and adjust .vscodeignore

Not sure what caused the breakage now but since the error message
complains about missing tsc, here we install typescript explicitly.

https://source.cloud.google.com/results/invocations/fc221c68-5ed5-4e30-968e-66736d024092/targets/golang%2Fvscode-go%2Fgcp_ubuntu%2Fpresubmit/log

Explicitly exclude .user-data-dir-test directory from vsce packaging.
Tests leave the directory (used as a fake user workspace) behind
and sometimes fail to clean up files under the directory. Those
files cause issues in vsce packaging.

Change-Id: I34f552d90d459a957f88c324c92187fc5b8bab10
Reviewed-on: https://go-review.googlesource.com/c/vscode-go/+/279693
Trust: Hyang-Ah Hana Kim <hyangah@gmail.com>
Run-TryBot: Hyang-Ah Hana Kim <hyangah@gmail.com>
TryBot-Result: kokoro <noreply+kokoro@google.com>
Reviewed-by: Suzy Mueller <suzmue@golang.org>

.vscodeignore

@@ -1,14 +1,16 @@
 **/*.map
 **/tslint.json
-.github/**/*
+.git/
+.github/
 .gitignore
 .prettierrc.json
-.vscode-test/**
+.user-data-dir-test/
 .vscode/
+.vscode-test/
 SECURITY.md
 build/
 docs/
-node_modules
+node_modules/
 out/
 src/
 test/

build/Dockerfile

@@ -27,7 +27,7 @@ ENV PATH /workspace/vscodego/go/bin:/go/bin:/usr/local/go/bin:${PATH}
 ENV DEBIAN_FRONTEND noninteractive
 
 RUN apt-get update && apt-get install -y libnss3 libgtk-3-dev libxss1 libasound2 xvfb libsecret-1-0
-RUN npm install -g vsce
+RUN npm install -g typescript vsce
 
 WORKDIR /workspace
 ENTRYPOINT ["build/all.bash"]