src/app/item-page: set max-width to 75 characters

Set max-width of item-page-field components to 75 characters. This
is in line with some best practices regarding readability, though
may need to be adjusted in the future.

See the following recommendations:
  - 50 to 75 characters: https://baymard.com/blog/line-length-readability
  - 60 to 80 characters: https://pimpmytype.com/line-length-line-height/
  - 50 to 75 characters: https://www.uxpin.com/studio/blog/optimal-line-length-for-readability/
  - 50 to 75 characters: https://medium.com/@wblekhoa/talk-aboutthe-optimal-length-of-text-in-ux-ui-525e689f0b71

Author: alanorth

src/app/item-page/simple/field-components/specific-field/item-page-field.component.html

@@ -1,4 +1,4 @@
-<div class="item-page-field">
+<div class="item-page-field" style="max-width: 75ch;">
   <ds-metadata-values
     [mdValues]="item?.allMetadata(fields)"
     [separator]="separator"