Check all functions with workflow.Context as first parameter

[ndtretyak]

Instead of checking only arguments of RegisterWorkflow consider all functions like func (workflow.Context, ...) ... as workflow definitions (or functions called from workflows).

Closes #1207

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[cretz]

Nice, thanks! May need to sign CLA (sorry if CLA thing is acting up).

Can you show an example of the CLI output for:

func MyWorkflow(workflow.Context) error {
    doSomething()
}

func doSomething() {
  doSomethingElse()
}

func doSomethingElse() {
  time.Now()
}

I want to make sure that this still shows the tree, though I'm sure it does.

[ndtretyak]

Well, I should have tried to run the CLI myself. It turned out that workflow.Context belongs to go.temporal.io/sdk/internal rather than go.temporal.io/sdk/workflow. But in unit tests this is not the case.

After adding an additional check for the internal package I got the following graph

go.temporal.io/sdk/contrib/tools/workflowcheck/workflow/testdata/src/a.MyWorkflow is non-deterministic, reason: calls non-deterministic function go.temporal.io/sdk/contrib/tools/workflowcheck/workflow/testdata/src/a.doSomething
  go.temporal.io/sdk/contrib/tools/workflowcheck/workflow/testdata/src/a.doSomething is non-deterministic, reason: calls non-deterministic function go.temporal.io/sdk/contrib/tools/workflowcheck/workflow/testdata/src/a.doSomethingElse
    go.temporal.io/sdk/contrib/tools/workflowcheck/workflow/testdata/src/a.doSomethingElse is non-deterministic, reason: calls non-deterministic function time.Now
      time.Now is non-deterministic, reason: declared non-deterministic

[cretz]

Looks great to me! Will let @Quinn-With-Two-Ns take a look.

[Quinn-With-Two-Ns]

LGTM makes more sense for it to work this way to me