Remove svg assets from the build/dist

[huwshimi]

This work was started in #3833 but that PR was never merged.

[huwshimi]

QA:

• clean-all and build the gui
• load the gui and add some apps/relations
• check that the relation icons appear correctly
• open the df and check that the select boxes have the chevron in them

[hatched]

QA Notes: When dragging the create-relation icon the circle that follows the cursor does not have the icon in it but it does in develop.

[huwshimi]

Thanks @hatched, could you please QA again?

[hatched]

Thanks @huwshimi