Online presence icons and links

[thisismydesign]

Prerequisite: #22

• Add separate configuration entry for "Online presence icons" which holds a mapping of text to resources, e.g. {github: path_to_gh_logo, website: path_to_website_logo, instagram: path_to_instagram_logo, ... }
  • similar to tech icons as defined in https://github.com/c-hive/c-hive.dev/issues/22
• Add configuration entry for Online presence, e.g. {github: https://github.com/c-hive, ...}
• Display online presence links on the top right below day/night mode switch

For reference see from #18:

[nkapolcs]

Resolved by #90