✨[RUMF-373] Add View load duration and load type

[mquentin]

What it does

Implement a load duration for each collected View.
This duration starts at the View start time and end when there is no loading activity for a given time.
As the view load occurs before any possible user actions, the collection of user action starts right after.

In addition, a view loading type is collected in view to identify initial page load and route change as any new view is loaded.

Context

View load and User actions need to have separated lifecycle. The view loading mode needs to be identify.

Change

• Prevent UA collection during the view load
• Collect the loading mode
• Test UA collection and View loading lifecycles
• Test view loading mode scenarios

[BenoitZugmeyer]

This looks nice!

I think that we could make things simpler and easier to understand by moving some parts around:

• userActionCollection should expose a cancelCurrentUserAction function that viewCollection could call to cancel a potential user action

• a new utility module could be created to track page activities, and move some of the useraction code into it. It could expose a function like waitPageIdle(callback: (endTime: number | undefined) => void): { stop(): void }, that would be used by both userActionCollection and viewCollection.

By doing this, we shouldn't need a new lifecycle event (VIEW_LOAD_COMPLETED). The viewCollection logic would not use functions named waitUserActionCompletion (this is unintuitive: I understand that loadDuration follows the same logic than useraction, but it should not be based on it).

We can talk about this if it's unclear!

[codecov-io]

Codecov Report

Merging #388 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #388   +/-   ##
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  Coverage   86.95%   86.95%           
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  Files          31       31           
  Lines        1733     1733           
  Branches      348      348           
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  Hits         1507     1507           
  Misses        226      226           

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[BenoitZugmeyer]

OK for me, I have two last small comments, but it looks fine otherwise!