R: support Build / Test / Check keybindings for R projects

[kevinushey]

I know we discussed allowing this to be provided by a separate extension (and I think that's the right solution long-term) but as a stop-gap I think we should at least provide the following keybindings in R package projects:

• Cmd + Shift + B: run devtools::install() in a terminal;
• Cmd + Shift + T: run devtools::test() in a terminal;
• Cmd + Shift + E: run devtools::check() in a terminal;

Otherwise, prospective users of Positron who are R package developers will feel hamstrung when trying to get started.

[kevinushey]

Alternatively, we could ask users to add the following .vscode/tasks.json file to their projects:

{
    // See https://go.microsoft.com/fwlink/?LinkId=733558
    // for the documentation about the tasks.json format
    "version": "2.0.0",
    "tasks": [
        {
            "label": "R: Build Package",
            "type": "shell",
            "command": "R CMD INSTALL --preclean .",
            "problemMatcher": [],
            "group": {
                "kind": "build",
                "isDefault": true
            }
        },
        {
            "label": "R: Test Package",
            "type": "shell",
            "command": "R -e 'devtools::test()'",
            "problemMatcher": [],
            "group": {
                "kind": "test",
                "isDefault": true
            }
        },
        {
            "label": "R: Check Package",
            "type": "shell",
            "command": "R -e 'devtools::check()'",
            "problemMatcher": [],
            "group": {
                "kind": "none",
                "isDefault": false
            }
        }
    ]
}

Then, one can use Cmd + P, type 'task', and then select one of the tasks to execute.

[romainfrancois]

related to #28

[jmcphers]

These keybindings are already taken in VS Code (e.g. Cmd + Shift + E toggles focus on the Explorer view) so I am hesitant to override them with RStudio bindings, even in R Package projects, unless the user really wants RStudio keybindings (see #669).

[jmcphers]

I believe these are implemented now.

[lionel-]

All of these have been implemented 👍