feat: add LogWriter field

[dwisiswant0]

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Summary

This pull request adds the LogWriter field and makes corresponding code changes in the teler package to ensure that log messages are written to the LogWriter in addition to other destinations if it is provided. It clarifies the behavior of the LogWriter field in the documentation and ensures that log messages are correctly routed to the custom LogWriter when it is non-nil.

Proposed of changes

This PR fixes/implements the following bugs/features:

• 91

How has this been tested?

Proof:

go test -v -race -run "TestNewWithLogWriter"

Closing issues

Fixes #

Checklist:

• [x] My code follows the code style of this project.
• [x] My changes successfully ran and pass linters locally (run make lint).
• [x] I have written new tests for my changes.
  • [x] My changes successfully ran and pass tests locally.
• [x] My change requires a change to the documentation.
  • [x] I have updated the documentation accordingly.

[codecov-commenter]

Codecov Report

All modified lines are covered by tests :white_check_mark:

Comparison is base (209249e) 75.67% compared to head (7c36ae9) 75.80%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #103 +/- ## ========================================== + Coverage 75.67% 75.80% +0.13% ========================================== Files 6 6 Lines 1106 1112 +6 ========================================== + Hits 837 843 +6 Misses 217 217 Partials 52 52 ``` | [Files](https://app.codecov.io/gh/kitabisa/teler-waf/pull/103?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=kitabisa) | Coverage Δ | | |---|---|---| | [teler.go](https://app.codecov.io/gh/kitabisa/teler-waf/pull/103?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=kitabisa#diff-dGVsZXIuZ28=) | `77.27% <100.00%> (+0.33%)` | :arrow_up: |

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