CHE-9265: Implementation Theia terminal plugin.

[AndrienkoAleksandr]

Implementation Theia terminal plugin

This pull request implements server and client side for creation multi-machine terminals in the Eclipse CHE workspaces(for docker environment). Client side and server side communicate with help websocket connections(protocol json-rpc). To manage all terminals used separated json-rpc connection, one per client. To send input/output of the terminal uses separated simple websocket connection.

Terminal Server

Server side was written on the go-lang and uses docker cli to create terminal connections. Terminal connection based on docker exec.
Server side supported:

• Create new terminal exec;
• Connect to the created terminal exec;
• Resize terminal exec;
• Ability to reconnect to the created terminal exec with restore content. Restore content implemented like ring buffer with size 1000 lines.
  Kill terminal doesn't supported yet, because docker api doesn't support kill exec. See more: kill exec proposal
  For dependencies management used dep tool https://github.com/golang/dep.

Terminal client

For now client side it's Theia Extension based on original Theia terminal extension, but modificated to support connection to the external server side. And this extension support ability select machine to terminal creation from command palette machine list. Minimal Theia core 0.3.8.

[AndrienkoAleksandr]

Don't review "vendor" directory it's external dependencies controlled by dep tool.

[AndrienkoAleksandr]

Creation CQ's in progress.

[AndrienkoAleksandr]

Needed eclipse-che/che#9475

[benoitf]

Don't review "vendor" directory it's external dependencies controlled by dep tool.

is this directory has to be checked in in the repository ? https://golang.github.io/dep/docs/FAQ.html#should-i-commit-my-vendor-directory

[AndrienkoAleksandr]

I think, we can save all used dependencies to have stable reproducible build protected with changes history of upstream projects. And for our go-lang agents we saved sources of external dependencies in the vendor folder, but we did it with help Godeps(for now this project is archived and recommends to use dep tool). We skips test tool and unused packages form upstream projects:
[prune]
go-tests = true
unused-packages = true

[skabashnyuk]

How is this feature is going to work in OpenShift/Kubernetes environments?

[ghost]

@skabashnyuk it won't.

[AndrienkoAleksandr]

CQ for docker(moby) cli https://dev.eclipse.org/ipzilla/show_bug.cgi?id=16187

[azatsarynnyy]

term's type is Xterm.Terminal. Is there any reason to use type assertion to any?

[AndrienkoAleksandr]

Nice catch.

[azatsarynnyy]

A lot of variables within the PR are declared as let but they're actually constants. Should they be declared as const?

[AndrienkoAleksandr]

Yes, it should be. Done.

[AndrienkoAleksandr]

xterm.js 3.3.0 CQ https://dev.eclipse.org/ipzilla/show_bug.cgi?id=16190

[AndrienkoAleksandr]

CQ xterm.js 3.3.0 https://dev.eclipse.org/ipzilla/show_bug.cgi?id=16190 approved.

[AndrienkoAleksandr]

awaiting for CQ for docker(moby) cli.