Declare in corresponding header files and dissolve main.h (#3796)

* Declare in corresponding header files and dissolve main.h

Apply include-what-you-use

* Remove further unncessary includes

* Incorporate review comment

* Do not declare static functions and variables in header

* Adapt test

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

test/make_tc_task.cpp

@@ -28,16 +28,12 @@
 // cmake.h include header must come first
 
 #include <CmdInfo.h>
-#include <main.h>
 #include <stdlib.h>
 #include <taskchampion-cpp/lib.h>
 #include <test.h>
 #include <util.h>
 
 #include <iostream>
-#include <limits>
-
-#include "format.h"
 
 namespace {