Refactor function actions on cauchy approximations

[malarbol]

This PR introduces the new modules:

• action-on-cauchy-approximations-isometries-pseudometric-spaces.lagda.md;
• action-on-cauchy-approximations-short-maps-metric-spaces.lagda.md;
• action-on-cauchy-approximations-short-maps-pseudometric-spaces.lagda.md.

to refactor these concepts in their own modules.

[malarbol]

Because we didn't have Cauchy pseudocompletions at the time, the definitions of these actions were in the cauchy-approximations-XXX modules while the fact that they induce short maps / isometries were in the cauchy-pseudocompletions-XXX modules.

[fredrik-bakke]

Since you're already taking the opportunity to fix some names across the board, would you be so kind to also change the naming pattern short-function- to short-map-?

[malarbol]

Since you're already taking the opportunity to fix some names across the board, would you be so kind to also change the naming pattern short-function- to short-map-?

There are ~500 occurrences of short-function- across ~50 modules, so I think it would be better to do this change in a dedicated PR or in the same PR dedicated to #1621 with a coherent naming scheme between short maps and expansive maps.