feat(datepicker): Add optional "today" button

[pjlinn]

Add button for user to easily set today's date. Samples heavily from, and finishes closed PR: #5024

Potentially resolves #5680

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• added/updated tests.
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• added/updated demos.

[daniloff200]

I'm not sure, maybe I did something wrong, but, I wasn't able to see the button.
The same case, as it was for #5024, but, there was no demo at all. Here we have it, but, it looks like it doesn't work correctly

Does it work for you @pjlinn ?

[pjlinn]

Hey @daniloff200 , thanks for reviewing. I pulled in latest development and re-ran locally and it seems to be working. Screen shot taken after running the steps:

npm run build.watch // in first terminal
ng serve // in second

Is there a better command to verify it is working locally?

[daniloff200]

That's strange, I just completely rebuild all the app, and now it works
haha
🤣 😄
Well, looks good in general, I have an idea to make a positioning for this button, like, center,left,right

Gonna add some param for that later, and merge that

Thanks for your help, @pjlinn !!!

[pjlinn]

No worries! Thank you again for the review (and ngx-bootstrap in general) 👍

Good idea about position.