feat(teler): add CaddyHandler{,FuncWithNext}

[dwisiswant0]

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Summary

Adds

• CaddyHandler method,
• CaddyHandlerFuncWithNext method.

Proposed of changes

This PR fixes/implements the following bugs/features:

• Bug 1
• Bug 2
• Feature 1
• Feature 2
• Breaking changes

How has this been tested?

Proof:

Closing issues

Fixes #

Checklist:

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

[codecov]

Codecov Report

Attention: Patch coverage is 53.33333% with 7 lines in your changes missing coverage. Please review.

Project coverage is 78.27%. Comparing base (5974890) to head (192180e).
Report is 3 commits behind head on master.

Files	Patch %	Lines
handler.go	53.33%	5 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #199      +/-   ##
==========================================
- Coverage   78.67%   78.27%   -0.41%     
==========================================
  Files          12       12              
  Lines         933      948      +15     
==========================================
+ Hits          734      742       +8     
- Misses        132      137       +5     
- Partials       67       69       +2     

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