refactor common code in CI pipelines (#18035)

* refactor CI with nimInternalInstallDepsWindows

* refactor CI with nimInternalBuildKochAndRunCI

* fixup

.github/workflows/ci_docs.yml

@@ -59,11 +59,9 @@ jobs:
         if: runner.os == 'Windows'
         shell: bash
         run: |
-          mkdir dist
-          curl -L https://nim-lang.org/download/mingw64.7z -o dist/mingw64.7z
-          curl -L https://nim-lang.org/download/dlls.zip -o dist/dlls.zip
-          7z x dist/mingw64.7z -odist
-          7z x dist/dlls.zip -obin
+          set -e
+          . ci/funs.sh
+          nimInternalInstallDepsWindows
           echo "${{ github.workspace }}/dist/mingw64/bin" >> "${GITHUB_PATH}"
 
       - name: 'Add build binaries to PATH'