refactor common code in CI pipelines (#18035)

* refactor CI with nimInternalInstallDepsWindows

* refactor CI with nimInternalBuildKochAndRunCI

* fixup

tools/ci_generate.nim

@@ -29,15 +29,11 @@ tasks:
     set -e
     cd Nim
     . ci/funs.sh && nimBuildCsourcesIfNeeded
-    $nim_csources c --skipUserCfg --skipParentCfg koch
     echo 'export PATH=$HOME/Nim/bin:$PATH' >> $HOME/.buildenv
 - test: |
     set -e
     cd Nim
-    if ! ./koch runCI; then
-      nim r tools/ci_testresults.nim
-      exit 1
-    fi
+    . ci/funs.sh && nimInternalBuildKochAndRunCI
 triggers:
 - action: email
   condition: failure