[Snackbar] - fix button position with long texts

[avocadowastaken]

• PR has tests / docs demo, and is linted.
• [ x Commit and PR titles begin with [ComponentName], and are in imperative form: "[Component] Fix leaky abstraction".
• Description explains the issue / use-case resolved, and auto-closes the related issue(s) (http://tr.im/vFqem).

Fix for #4676

[mpontikes]

@oliviertassinari Can you review this PR?

[avocadowastaken]

@mpontikes it has problems in ff, need to replace with flex maybe

[oliviertassinari]

I only had a quick view at this PR.
Do we really want to display ... when the text is too long?
From the specification, I think that we should increase the height of the Snackbar.
Hence, looks like the root issue is the same as #4294.

Regarding a proper fix, I think that we should stop forcing the height of the element, take advantage of the browser layout CSS engine and use a bottom: 100% transform for the open / close stuff.

[avocadowastaken]

@oliviertassinari big 👍 For this,

I didn't wanted to bother about multiple lines in this PR because there is another issue about multi line snack bar, so I just add '...' At the end