Improve data, chart, calculus export/import icons

Improve readability of icon especially the arrow part.

Current state from editor:

Current state from result node:

Also try to use the blue arrow of the default Eclipse Export command? ()

Some resources: https://gitlab.huma-num.fr/txm/txm-src/-/tree/main/resources/icons/export?ref_type=heads

Also use the same icon for export chart from node and export chart from editor.