Website Gallery page building (#850)

* initial draft

* update dependences, add antd for layout (note yarn install needed her)

* update gallery to use mdx file format to support react components

* add custom react component for gallery with tag based filtering and url state management

* add styling for gallery objects

* add gallery data structure and default image

* improve layout for gallerypage

* revise Postgres demo

* add default value when image is not provided

* move semetic kernal to ecosystem

* update tags

* update tags

* update ecosystem

* update default fig

* update tags

* reformat

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Co-authored-by: “skzhang1” <“shaokunzhang529@gmail.com”>
Co-authored-by: Victor Dibia <victordibia@microsoft.com>