refactor: all files about templates and kubectl

[aFlyBird0]

Signed-off-by: Bird aflybird0@gmail.com

Pre-Checklist

Note: please complete ALL items in the following checklist.

• I have read through the CONTRIBUTING.md documentation.
• My code has the necessary comments and documentation (if needed).
• I have added relevant tests

Description

1. move the template related code from /internal/pkg/file to /pkg/util/template
2. refactor the template package, see the code comments in /pkg/util/template for details
3. Modify all related code in the project to use the new template package
4. refactor the kubectl package to include the installer and util parts.

New Behaviors

1. template

2. kubectl

[steinliber]

I think this refactor is great and more clear, you should add more test in pkg/util/template beacuse many func will invoke this module

[aFlyBird0]

I think this refactor is great and more clear, you should add more test in pkg/util/template beacuse many func will invoke this module

Thank you for your review and suggestion. I will add more uts as possible as I can.

[iyear]

LGTM