fix: disable display-signs on floating windows

[triarius]

The filetype exclusions are not the best way to disable the mark signs on certain windows as the filetype is a property of the buffer, while floating is a property of the window. The same filetype could be displayed differently depending on whether its window is floating or not. I think most users are unlikely to want these in floating windows, so I disabled them entirely. I'd be happy to make this configurable, but I think the default should be that they are not shown, as typically the normal editing workflow does not apply to floating windows.

In my case, they appear in LSP hints, which are not intended to hold a cursor. It also makes the content no longer fit in the window.

Fixes: #60

Screenshots for LSP

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Screenshots for Neo Tree

Ignore the line numbers, they are caused by a different plugin.

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