feat(layer-list)Allow search with layer keyword (capabilitie or context)

[pelord]

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)
Into the mapDetails tool, layer list could be controled/subsetted by

• layer title
• type
• visiblity (visible or in scale range)

What is the new behavior?
Adding a way to control/subset by keyword.

The keyword could be provided by 2 ways:

1. "optionsFromCapabilities": true, ==> wms layer's keywords
2. "metadata": {
   "keywordList": ["your","own","keyword", "list"]
   }

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: