fix: display ogc-filter-button:

[hugbe8]

Please check if the PR fulfills these requirements

• The commit message follows our guidelines:https://github.com/infra-geo-ouverte/igo2/blob/master/.github/CONTRIBUTING.md#git-commit-guidelines
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

What is the current behavior? (You can also link to an open issue here)
The toggle button not displaying correctly in ie11. The style flex option is not applied. (link with pullRequest #414)

What is the new behavior?

• The toggle button now displaying correctly in ie11.
• Space saving to around the pushButton

- fix ie11:
	.mat-button-toggle { display: inline-flex; }
	.igo-layer-button-group { max-width: 100%; }
- ajust style (space saving): .mat-list-item { height: auto; }
- ajust style (space saving): .igo-layer-button-group { contents; } /* Note: ie11 equivalent: display: ruby-base; ... no polyfills found */

Does this PR introduce a breaking change? (check one with "x")

[ ] Yes
[x] No

If this PR contains a breaking change, please describe the impact and migration path for existing applications:

Other information: