Update chart.js from 2.9.4 to 3.9.1.

[yubiuser]

What does this PR aim to accomplish?:

Update chart.js from 2.9.4 to 3.9.1.
Needed to add chartjs-adapater-moment.js. I tried to be as close as possible to the old visual style. A few unnecessary options were removed, some defaults were explicitly set (e.g. responsive: true).

Useful for review: https://www.chartjs.org/docs/3.4.1/getting-started/v3-migration.html

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2. I have commented my proposed changes within the code and I have tested my changes.
3. I am willing to help maintain this change if there are issues with it later.
4. It is compatible with the EUPL 1.2 license
5. I have squashed any insignificant commits. (git rebase)

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[tingreavinash]

Hi @yubiuser,

I want to contribute to AdminLTE project, can you please help with local setup (Windows) of this project?
I have installed NPM, Cloned this repo, npm install, but not able to run the project ..

[yubiuser]

Do you have a webserver installed?

[tingreavinash]

Do you have a webserver installed?

@yubiuser, Yes, I have xampp server..

[yubiuser]

The webinterface is tightly coupled with the Pi-hole binary FTL which provides all the data. This binary doesn't run on Windows, but Linux. You could surely make changes to the interface without having a working Pi-hole instance, but usually your better of if you have the complete setup. I run Linux myself and edit the files directly within the web dir /var/www/html/admin which is a git clone of the repo.
I know @rdwebdesign is using Windows (not 100% sure for development), maybe he could explain his setup.

[DL6ER]

Thanks for this PR. I had only limited time for testing this morning but I'll try to return to it later. It looks good to me, the only issue I've seen so far is a misplacement of the loading spinners:

edit I've just seen that this is an issue on devel, too.

[rdwebdesign]

I also see the spinners on the same place in master.

I think the spinners are there since a long time ago.

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Edit:
Before attempt any modifications, I was trying to understand where the spinners supposed to be placed and what happened.
I found out this was probably caused by this commit.

The spinner uses a fontawesome icon. This icon is replaced (and resized and repositioned) by script.
This change was made almost 2 years ago.

[yubiuser]

Spinner is fixed by #2385