Add KAS architecture to GitLab Cells

What does this MR do and why?

What

1. Add KAS to be cell local
2. Created a more detailed architecture diagram for KAS

Why

1. Things end up simpler since we don't have a global service
2. Adding this amount of detail to the main architecture diagram will end up being noisy, having a separate diagram will help split the information.

Reference: &11710 (closed)

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Before	After
source	source