Add debug configuration options for test debug codelens

[lggomez]

This PR adds a new runtest.debugConfig setting inside of go.enableCodeLens that mimicks the launch.json options for delve, so we can configure the test debugger
Fixes #1735

An example user setting using this feature:

    "go.enableCodeLens": {
        "runtest": true,
        "runtest.debugConfig": {
            "useApiV1": false,
            "dlvLoadConfig": {
                "followPointers": true,
                "maxVariableRecurse": 1,
                "maxStringLen": 128,
                "maxArrayValues": 128,
                "maxStructFields": -1
            }
        }
    },

[lggomez]

@ramya-rao-a PTAL

[ramya-rao-a]

@lggomez This will not help the case where we can debug programs even without the presence of the launch.json file

I would suggest to add a new setting called go.delveConfig which has the below properties

• useApiV1
• dlvLoadConfig

[lggomez]

@ramya-rao-a Done. Regarding the launch config, actually this doesn't depend on launch.json, it was just a bad variable naming from a previous test

[ramya-rao-a]

The same needs to be done in the resolveDebugConfiguration method at https://github.com/Microsoft/vscode-go/blob/master/src/goDebugConfiguration.ts. So we should probably move this to the util.ts file

This is what is used when we debug "main" programs without any launch.json files

[lggomez]

Ok, so I unified the default configurations for both normal and test codelens debug. This should get rid of the confusion caused by this difference, plus being configurable for delve

[ramya-rao-a]

@lggomez While testing this I realized that all debug configurations (whether the ones from launch.json, or the ones we create for debug tests codelens or the default ones) pass through resolveDebugConfiguration. So that single location is more than enough to read the dlv config from the configuration/settings.

Sorry about all the churn

[merlijn-sebrechts]

For anyone here to show long strings in the inspector; add this to vscode user settings. You need to increase both maxStringLen and maxArrayValues to show longer strings.

    "go.delveConfig": {
        "useApiV1": false,
        "dlvLoadConfig": {
            "maxStringLen": 600,
            "maxArrayValues": 600,
        }
    },