chore: require explicit-function-return-type

[samayer12]

Description

Promotes linter rule from a warning to an error.

End to End Test:
(See Pepr Excellent Examples)

Related Issue

Fixes #1780

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Other (security config, docs update, etc)

Checklist before merging

• Unit, Journey, E2E Tests, docs, adr added or updated as needed
• Contributor Guide Steps followed

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 82.11%. Comparing base (7cc69ea) to head (5ac5a41).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1781   +/-   ##
=======================================
  Coverage   82.11%   82.11%           
=======================================
  Files          52       52           
  Lines        2214     2214           
  Branches      436      469   +33     
=======================================
  Hits         1818     1818           
+ Misses        394      367   -27     
- Partials        2       29   +27     

see 7 files with indirect coverage changes