feat(format): allow formatting of all types of pointers

[Viatorus]

• const and volatile void pointers are directly formatted
• other pointer types (e.g. int*) can be formatted by using emio::ptr(...) (like fmt::ptr)

Fixes #69

[codecov-commenter]

Codecov Report

All modified lines are covered by tests ✅

Comparison is base (1f161cf) 99.40% compared to head (cf39a07) 99.40%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #72   +/-   ##
=======================================
  Coverage   99.40%   99.40%           
=======================================
  Files          56       56           
  Lines        5869     5891   +22     
=======================================
+ Hits         5834     5856   +22     
  Misses         35       35           

Files	Coverage Δ
include/emio/detail/format/formatter.hpp	98.72% <100.00%> (ø)
include/emio/formatter.hpp	100.00% <100.00%> (ø)
test/unit_test/test_format.cpp	99.64% <100.00%> (+<0.01%)	⬆️

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.