Implement KEYS command

[kelvinmwinuka]

Implement the KEYS command, which returns all the keys that match the provided pattern.
Reference: https://redis.io/docs/latest/commands/keys/

Client-Server Spec:

Command File: ./internal/modules/generic/commands.go
Test File: ./internal/modules/generic/commands_test.go

Command: keys
Module: constants.GenericModule
Categories: constants.KeyspaceCategory, constants.ReadCategory, constants.SlowCategory, constants.DangerousCategory
Description: (KEYS pattern) Returns an array of keys that match the provided glob pattern.
Sync: false

Embedded Spec:

Command File: ./echovault/api_generic.go
Test File: ./echovault/api_generic_test.go

NOTE: You may have to edit the HandlerFuncParams type to include a function that returns all matching keys.

[tristin-codes]

I have started implementing this here: tristin-codes@94a946e