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 :white_check_mark:

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

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #72 +/- ## ======================================= Coverage 99.40% 99.40% ======================================= Files 56 56 Lines 5869 5891 +22 ======================================= + Hits 5834 5856 +22 Misses 35 35 ``` | [Files](https://app.codecov.io/gh/Viatorus/emio/pull/72?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Toni+Neubert) | Coverage Δ | | |---|---|---| | [include/emio/detail/format/formatter.hpp](https://app.codecov.io/gh/Viatorus/emio/pull/72?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Toni+Neubert#diff-aW5jbHVkZS9lbWlvL2RldGFpbC9mb3JtYXQvZm9ybWF0dGVyLmhwcA==) | `98.72% <100.00%> (ø)` | | | [include/emio/formatter.hpp](https://app.codecov.io/gh/Viatorus/emio/pull/72?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Toni+Neubert#diff-aW5jbHVkZS9lbWlvL2Zvcm1hdHRlci5ocHA=) | `100.00% <100.00%> (ø)` | | | [test/unit\_test/test\_format.cpp](https://app.codecov.io/gh/Viatorus/emio/pull/72?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Toni+Neubert#diff-dGVzdC91bml0X3Rlc3QvdGVzdF9mb3JtYXQuY3Bw) | `99.64% <100.00%> (+<0.01%)` | :arrow_up: |

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