feat(auth): SASL SCRAM-SHA-256 support

[jgoux]

What kind of change does this PR introduce?

feature

What is the current behavior?

pg-gateway doesn't support SASL authentication

What is the new behavior?

add support for SASL SCRAM-SHA-256 authentication method

[jgoux]

Sorry it took me so long and I refactored a lot of code. 😓

Basically I wanted the message flow to be clearer, so I used explicit steps and a few switches in the PostgresConnection class to route the messages to their appropriate handlers.

Here are the main changes:

• Formatting and linting is setup with Biome
• New scram-sha-256 auth flow support
• All the authentication flows are contained in their own class, implementing the same interface AuthFlow.
• The message buffering logic is now contained in its own class.
• The TLS upgrade logic is contained in its own class
• pglite example is turned into a pglite-auth example, where each auth flow is showcased.
• The auth.mode option is now named auth.method, and each method is named after what can be put in pg_hba.conf
• The validateCredentials option is now optional, we provide a default validation function, but it can be override if the user specifies the option.
• Most auth flows require the user to define a callback to obtain the relevant password/hash/auth data:
  • password: getStoredPassword
  • md5: getPreHashedPassword
  • scram-sha-256: getScramSha256Data
  • trust: trustMeBro (ok this one is a joke and is not included 😂)

[gregnr]

Nice work