Add new features to custom tooltip

[2alin]

This fixes #370, fixes #371, fixes #372 and continues #361.

@klahnakoski
It looks quite amazing, I think you will feel as proud as I feel right now. 😁

Tooltip on action (12s): https://youtu.be/2j-5VvuG08Q

To consider: sometimes the tooltip arrow looks like it's in the wrong position (a little) compared to the data point, but that's chartjs fault. Just for testing, I rendered the custom and default tooltips at the same time, and both arrow tips match (almost) perfectly: (39s) https://youtu.be/Vn5xAwOEHWs (recorded before the locking feature).

More comments in the code.

ping: @armenzg @aimenbatool

[2alin]

@klahnakoski I've commented some stuff worth to point out.

[klahnakoski]

This looks very good, and it is clearly solves the immediate problem. I will add @aimenbatool as a reviewer because she had the sharp eyes to catch what I missed last time.

[klahnakoski]

@aimenbatool may you check to see if anything else is missed? I am unable to set you as a reviewer formally.

thank you!

[klahnakoski]

@2alin We will wait for @aimenbatool to chime in. If you have any other PRs, be sure to base them off of this branch, which should be merged by Monday morning.

[aimenbatool]

@2alin @klahnakoski Great work. This looks perfect.

I will take some time out and definitely read the code. 👏👏👏

A quick thing: When we click one data point and lock it then we can't see any other data point on mouse hover.
Here is what is happening:

• We can see data details on first time hovering
• We click & lock data point
• We now move the mouse and this time we don't see data details on mouse hover (which was happening earlier)
• We can see data details upon clicking only after the first click

Drawback: We will have to click an unknown data point and lock it to see details.

This is the behavior I'm talking about. Deploy #242 and check.

@armenzg can tell better if it is good to add it back or not.

Rest is an awesome work @2alin :)

[klahnakoski]

@aimenbatool thank you for noticing that subtle behaviour. I added it as another issue.