Fix extension vsix

[kubukoz]

I think this is due to microsoft/vscode-vsce#432 : the modules in question don't appear to be packaged in the VSIX if not listed explicitly.

This is sort of a workaround to fix 0.0.9, which currently fails to launch with the following output in the extension host logs:

2023-05-10 17:57:02.530 [error] Activating extension disneystreaming.smithy failed due to an error:
2023-05-10 17:57:02.530 [error] Error: Cannot find module 'concat-map'
Require stack:
- /Users/kubukoz/.vscode/extensions/disneystreaming.smithy-0.0.9/node_modules/brace-expansion/index.js
- /Users/kubukoz/.vscode/extensions/disneystreaming.smithy-0.0.9/node_modules/minimatch/minimatch.js
- /Users/kubukoz/.vscode/extensions/disneystreaming.smithy-0.0.9/node_modules/vscode-languageclient/lib/common/diagnostic.js
- /Users/kubukoz/.vscode/extensions/disneystreaming.smithy-0.0.9/node_modules/vscode-languageclient/lib/common/client.js
- /Users/kubukoz/.vscode/extensions/disneystreaming.smithy-0.0.9/node_modules/vscode-languageclient/lib/node/main.js
- /Users/kubukoz/.vscode/extensions/disneystreaming.smithy-0.0.9/out/src/extension.js
- /Applications/Visual Studio Code.app/Contents/Resources/app/out/vs/loader.js
- /Applications/Visual Studio Code.app/Contents/Resources/app/out/bootstrap-amd.js
- /Applications/Visual Studio Code.app/Contents/Resources/app/out/bootstrap-fork.js