[RFE] Add write-kvp flag to Azure-init CLI

# Current situation
Azure-init is aiming to improve its modularity by adding flags for each feature. Currently, there is no mechanism to signal when a report is ready or when a failure occurs.

# Ideal future situation
We can invoke a single flag that initializes the KVP writer and sets up a tracing layer.

# Implementation options
- `azure-init --write-kvp`

# Additional information

These flags should not be exclusive. We want the ability to combine them with other flags in a single call to azure-init (e.g., `--write-kvp --configure-sshd`).