Move logger from pkg/logger to internal/logger

[mkcp]

Is your feature request related to a problem? Please describe.

Logger is intended as a small wrapper around log/slog that bakes in input validation, ctx setters / getters, some app-specific default configuration.

Describe the behavior you'd like

Logger is not intended to provide a stable API, so to avoid any downstream conflicts we're going to move it to internal. Consumers are welcome to copy and paste any of the patterns within if they find it useful, and inquire with the Zarf team to learn about why we chose to build it the way we have.

Additional context

Logger: https://github.com/zarf-dev/zarf/tree/main/src/pkg/logger

Component of: #3210

[mkcp]

Discussed this some more and closing this out. We'll keep logger in pkg to avoid creating any downstream issues for folks utilizing Zarf as a library.