ComponentInterface should declare the componentShouldUpdate function

[ghingis]

Stencil version:

 up to @stencil/core@1.15.0-2

I'm submitting a:
[ ] bug report
[x] feature request
[ ] support request

Current behavior:
ComponentInterface does not declare the componentShouldUpdate function as an implementable function

Expected behavior:
ComponentInterface should declare the componentShouldUpdate as an implementable function

Steps to reproduce:

• create a component that implements the ComponentInterface from @stencil/core
• check the functions that you can implement from ComponentInterface

Other information:
The code should be located at:
src\declarations\stencil-public-runtime.ts
L:375 - L:427