enhancement: Develop higher-res sprites, for in-mission resolution up to 2160p (4K)

[mefistotelis]

To support resolutions up to 2160p (aka 4K), we will need sprites with proper scales. Scaling in-game wouldn't look that good.
Before going this territory, we should wrap up 2K sprites as listed in #322 .

Scaling for these resolutions would be necessary to make the game look ok:

2560x1680
3200x1920
3840x2160

Panel scale factor within the game for 3840x2160 verified to be 8, meaning the size of smallest sprites we have needs to be multiplied 9x (=8+1) to get largest sprites for that resolution.

Sprites needed for in-game graphics, as named in swars-gfx repo:

font_sharp_cult-*-white
panel_dgren_marbl-*
panel_lblue_plain-*
panel_mblue_bevel-*
pointers-*
weapons-outline-*

Specific sizes needed - font (scaling bound to height):

font_sharp_cult-35-white
font_sharp_cult-40-white
font_sharp_cult-45-white

Specific sizes needed - pointers (scaling bound to height):

pointers-224
pointers-256
pointers-288

Specific sizes needed - weapons (scaling bound to width, but adjusted for height):

weapons-outline-63
weapons-outline-72
weapons-outline-81

Specific sizes needed - panels (scaling same as for weapons):

panel_dgren_marbl-224
panel_dgren_marbl-256
panel_dgren_marbl-288

panel_lblue_plain-224
panel_lblue_plain-256
panel_lblue_plain-288

panel_mblue_bevel-224
panel_mblue_bevel-256
panel_mblue_bevel-288

Note, these are sprites needed for in-mission play; for scaling the projector menus, there are different requirements.
(the menus will have a separate "issue")