Fixes occasional error during pre-commit hook runs where the kolibri package.json was empty

[rtibbles]

Summary

Slightly rejig api spec tools to prevent errors during the core-api-js pre-commit hook. Previously the kolbiri package package.json was loaded in module scope, which caused weird interactions while running the build_kolibri_package script, which would rewrite the package.json file.

References

No issue - just observed in multiple pre-commit runs on Github Actions and locally.

Reviewer guidance

I confirmed this fixed a persistence and recurrent instance of this when running in https://github.com/learningequality/kolibri/pull/13981

The best way to check this works is to make a change within the kolibri NPM package and then try to commit it - then confirm that the hook runs without errors.

[github-actions[bot]]

Build Artifacts

Asset type	Download link
PEX file	kolibri-0.19.0b2.dev0_git.95.gde50ddf7.pex
Windows Installer (EXE)	kolibri-0.19.0b2.dev0+git.95.gde50ddf7-windows-setup-unsigned.exe
Debian Package	kolibri_0.19.0b2.dev0+git.95.gde50ddf7-0ubuntu1_all.deb
Mac Installer (DMG)	kolibri-0.19.0b2.dev0+git.95.gde50ddf7.dmg
Android Package (APK)	kolibri-0.19.0b2.dev0+git.95.gde50ddf7-0.1.6-debug.apk
Raspberry Pi Image	kolibri-pi-image-0.19.0b2.dev0+git.95.gde50ddf7.zip
TAR file	kolibri-0.19.0b2.dev0+git.95.gde50ddf7.tar.gz
WHL file	kolibri-0.19.0b2.dev0+git.95.gde50ddf7-py2.py3-none-any.whl