Fix: Itemfilter StyleOverride access to selectionlist

[A-Behairi]

Introducing noShadow property in eox-selectionlist that enables it's rendering without a shadow root and giving access for styleOverride property of the eox-itemfilter to reach eox-selectionlist in primary (not inline) mode.

[lubojr]

Just to double check - this PR is going to fix the styleOverride for ItemFilter not working at the moment?

Storybook https://eox-a.github.io/EOxElements/?path=/docs/elements-eox-itemfilter--docs for ItemFilter does not interact anyhow to the changes of the styleOverride property or is the behavior inside storybook just a "nonreactivity" issue of the storybook itself?

[silvester-pari]

Just to double check - this PR is going to fix the styleOverride for ItemFilter not working at the moment?

Storybook https://eox-a.github.io/EOxElements/?path=/docs/elements-eox-itemfilter--docs for ItemFilter does not interact anyhow to the changes of the styleOverride property or is the behavior inside storybook just a "nonreactivity" issue of the storybook itself?

Yes and no - this PR fixes some styleOverride issues for the sub-component selectionlist, which currently isn't "reachable" for the override since it's located in a separate shadow root.

The non-reacting of the storybook example might be an other issue, could be that the styleOverride property is not yet reactive, means doesn't react on changes, only uses initial value.

Before investing too much effort into this, I'd like to come up with a good generic way for style overrides, see #325

[lubojr]

OK. My concrete use case why I asked was that since ItemFilter 0.9.0 -> 0.12.0 the way how styleOverride works has changed (if I understand it correctly from filterOptions.styleOverride to property called styleOverride) but also the structure of HTML elements which compose the ItemFilter single select changed. Therefore current overrides for GTIF Domain images do not work anymore and I am struggling to get it back working in a branch eurodatacube/eodash#2427.