Code changes to rename to Secret Push Protection

Overview

Related to #511969 (closed)

Since we are renaming pre-receive secret detection to secret push protection, we should update the code to reflect this. This includes renaming columns, policy checks, and other places. There is already an issue for customer facing updates: #462289 (closed).

Proposal

After we address the database column changes, we need to rename the following:

Other Code

• Rename all occurrences of pre_receive_secret_detection around the codebase.
• Rename all occurrences of pre_receive_secret_detection_enabled around the codebase.
• Rename all occurrences of pre_receive_secret_detection_available around the codebase.
• Rename all occurrences of the licensed feature.
• Rename all occurrences of the graphql mutation.
• Rename all occurrences of the saas feature.

Additionally, we may have to rename anything introduced in Address gaps in API support for Secret Push Pro... (&15160 - closed):

• Rename all API-related changes from Address gaps in API support for Secret Push Pro... (&15160 - closed).
• Rename all API-related changes from Enable SPP for all projects in a group via a ne... (&15840 - closed)

Introduce new project-level APIs to use secret push protection columns and point old ones to them. Mark the old APIs/endpoints as deprecated, and remove them in the next major version (%18.0).

Considerations

• We may need to double check how this affects the metric definition added in !156076 (merged).