[Grid] Add alignItems & alignContent properties

[sakulstra]

@oliviertassinari not sure if it makes sense to add alignContent to the interactive demo - at least not in the current format, as alignContent won't make any difference.

Breaking change

-        <Grid container xs={6} align="flex-end">
+        <Grid container xs={6} alignItems="flex-end">
           <Grid item>

Closes #8599

[oliviertassinari]

alignContent won't make any difference

@sakulstra It needs multiple lines to make a difference. I don't think that we should add it for a simple reason, more options are more overhead for our users and decrease the demo quality. Sure we could have changed it so the alignContent makes a difference, but I think that it misses the points.

Regarding visual regression tests, I think that it's optional, we can be lazy on this feature and wait regression/bugs to add some.

Looks good otherwise, good job 👍

[sakulstra]

@oliviertassinari i never worked with a tool like argos, so i want to fix it as a learning experience. The change on InteractiveGrid is intended(alignItems instead of align), but why is PositionedTooltips broken on argos? locally it seems to be the same like before the change.

[oliviertassinari]

@sakulstra Because of:
https://github.com/callemall/material-ui/blob/3fb316bc9aacdb8a8bca481c89b1dd1a8f04a5f5/test/regressions/tests/Tooltip/PositionedTooltips.js#L50

[sakulstra]

🙊 i didn't realize there was an actual test file for that :/ only looked at the docs 👍
Thanks for helping me out!

[oliviertassinari]

I have forgotten my laptop at the office. I can't merge anything before tomorrow.

[oliviertassinari]

@sakulstra Thanks :)