feat: Using global private environment to save secrets[INS-4715]

[cwangsmv]

Changes
Leverage global private environment to add built-in support secret management capabilities.
Add a new secret type environment key-value pair to store secret variables with the following features:

• Secret environment variables will add a vault prefix automatically to distinguish with normal environment variables. If you define a secret environment called foo, you need to input {{ vault.foo }} to use as environment variable
• Secret environment values are encrypted in the database
• Secret environment values are masked unless in environment editor/variable editor modal/using in request
• When the private environment is exported, a default placeholder string will replace its real value
• When user has rest the encryption key (aka: vault key) in other devices, all local secret environment variables will be removed

We also introduce a new term Vault Key.
Vault key is used to encrypt/decrypt secret environment variables, it is not synced to the cloud, so users need to save the key themselves.
User could reset the vault key, but this will remove local secret environments in all devices.
Add a new UI in Preferences page for management:

Vault secrets can be used in scripts if user set Enable vault in scripts in settings. (Only allow to get vault secret value, set/unset/clear methods are not allowd)
The pattern is

insomnia.vault.get(<vault_name>)

Tasks

• Add new UI for secret environment variables
• Secret environment variables processing logic
  • Mask value unless in editor and request
  • Encryption/Decryption logic
• Vault key UI
  • New vault key management UI in Preferences modal
  • API integration and SSE event handling
  • Vault key/hash CRUD operations
• Pre-requset & After-response support
• Add smoke test

[ihexxa]

Added some minor comments and tend to move forward as there're several rounds review before, but ideally we might still have more tests in the next as it is a relatively huge change.

[ihexxa]

nit: Probably need to to auto switch to kv mode for one user has been in the json mode?

[cwangsmv]

Good catch, I will add in a separate PR and add a test to cover this