Isolate loading and deployment of plugins

[akosyakov]

I'm trying to bundle builtin VS Code extensions: #3956 (comment)

Some of the extensions are mispackaged, or there are bugs in our code to parse manifest of certain extensions. Whenever the plugin system stumbles at such extension it throws and interrupts processing of consequent extensions.

Some call stacks which I get:

root ERROR Uncaught Exception:  SyntaxError: Unexpected token P in JSON at position 28873
root ERROR SyntaxError: Unexpected token P in JSON at position 28873
    at JSON.parse (<anonymous>)
    at HostedPluginReader.getPluginMetadata (/workspace/vscode-builtin-extensions/node_modules/@theia/plugin-ext/lib/hosted/node/plugin-reader.js:71:27)
    at /workspace/vscode-builtin-extensions/node_modules/@theia/plugin-ext/lib/hosted/node/plugin-service.js:119:47
    at Array.forEach (<anonymous>)
    at HostedPluginServerImpl.deployBackendPlugins (/workspace/vscode-builtin-extensions/node_modules/@theia/plugin-ext/lib/hosted/node/plugin-service.js:118:24)
    at PluginDeployerImpl.<anonymous> (/workspace/vscode-builtin-extensions/node_modules/@theia/plugin-ext/lib/main/node/plugin-deployer-impl.js:192:41)
    at step (/workspace/vscode-builtin-extensions/node_modules/@theia/plugin-ext/lib/main/node/plugin-deployer-impl.js:56:23)
    at Object.next (/workspace/vscode-builtin-extensions/node_modules/@theia/plugin-ext/lib/main/node/plugin-deployer-impl.js:37:53)
    at /workspace/vscode-builtin-extensions/node_modules/@theia/plugin-ext/lib/main/node/plugin-deployer-impl.js:31:71
    at new Promise (<anonymous>)

root ERROR [hosted-plugin: 9591] { Error: Cannot find module '/tmp/vscode-unpacked/configuration-editing-1.0.0.vsix/extension/out/extension'
    at Function.Module._resolveFilename (module.js:548:15)
    at Function.Module._load (module.js:475:25)
    at Function.module._load (/workspace/vscode-builtin-extensions/node_modules/@theia/plugin-ext-vscode/lib/node/plugin-vscode-init.js:94:33)
    at Module.require (module.js:597:17)
    at require (internal/module.js:11:18)
    at Object.loadPlugin (/workspace/vscode-builtin-extensions/node_modules/@theia/plugin-ext/lib/hosted/node/plugin-host-rpc.js:68:28)
    at PluginManagerExtImpl.$init (/workspace/vscode-builtin-extensions/node_modules/@theia/plugin-ext/lib/plugin/plugin-manager.js:123:44)
    at RPCProtocolImpl.doInvokeHandler (/workspace/vscode-builtin-extensions/node_modules/@theia/plugin-ext/lib/api/rpc-protocol.js:173:23)
    at RPCProtocolImpl.invokeHandler (/workspace/vscode-builtin-extensions/node_modules/@theia/plugin-ext/lib/api/rpc-protocol.js:158:41)
    at RPCProtocolImpl.receiveRequest (/workspace/vscode-builtin-extensions/node_modules/@theia/plugin-ext/lib/api/rpc-protocol.js:122:45) code: 'MODULE_NOT_FOUND' }

I'm going to look into fixing packaging of VS Code extensions and individual parsing issues. Someone else can look into adding try - catch at cases where we loop over plugins.

[akosyakov]

Plugin which cannot be loaded is emmet. nls file has new line delimiters in values which are not get escaped during localization and lead to a bogus JSON. I would align localization with VS Code approach, i.e. instead of replacing variables in text, replace values in parsed JSON object, and add necessary code to isolate extension deployment.