SettingsGateway: The Final Rewrite

[kyranet]

Description of the PR

Prepares klasa for @klasa/settings-gateway.

Changes Proposed in this Pull Request (List new items in CHANGELOG.MD)

Added

• Added Unit Testing.
• Added examples for a large set of methods.
• Added bare null as an option to reset a key in SettingsFolder#{update}.
• Added Serializer#{validate,resolve} to allow further control on how SettingsGateway handles the data.
• Added context to the settingsUpdate and settingsCreate events, they contain the raw changes, guild, language, etc.
• Added extraContext to the SettingsFolderResetOptions type, this value is pased in all places (Serializer#validate, SchemaEntry#filter, settingsUpdate and settingsCreate events, and more).

Changed

• Tweaked Serializer#stringify's second argument from KlasaMessage to Guild | null.
• Tweaked Serializer#deserialize's arguments to (SerializableValue, SerializerUpdateContext).
• Renamed SchemaEntry#{min,max} to SchemaEntry#{minimum,maximum}.
• Tweaked SettingsFolder's value type to be more accurate.
• Tweaked SettingsFolderUpdateOptions's option to produce a TypeScript compiler error when arrayAction is set to 'overwrite' and arrayIndex is defined.
• Tweaked SettingsFolder#client to throw an error when it's uninitialized.
• Tweaked SettingsFolder#{reset,update} to return a much more useful struct.
• When specifying arrayIndex in SettingsFolder#update and arrayAction is defined as add, all entries will be inserted at given index.
• When specifying arrayIndex in SettingsFolder#update and arrayAction is defined as remove, as many entries as given will be removed from given index.
• When specifying arrayIndex in SettingsFolder#update and arrayAction is not defined or defined as auto, all entries will replace the existing ones.

Removed

• Removed throwOnError option in SettingsFolder#{reset,update}, they will now always throw when they encounter an error.

Fixed

• Resolved bug where Schema#get would throw an error if a path did not exist.
• Resolved bug where Schema#{add,remove} was still callable even after being initialized.
• Resolved bug where SettingsFolder#get would throw an error if a path did not exist.
• Resolved type bug in SettingsFolder#pluck.
• Resolved bug in SettingsFolder#resolve not resolving into objects when specifying a folder path.
• Resolved bug in SettingsFolder#reset where database conditions were not handled correctly.
• Resolved bug in SettingsFolder#update where options would sometimes type error.
• Resolved bug in SettingsFolder's patch function not allowing non-literal objects to be used.
• Resolved bug in SettingsFolder#{reset,update} patching after emit.
• Fixed the types from the Provider and SQLProvider classes.

Semver Classification

• This PR only includes documentation or non-code changes.
• This PR fixes a bug and does not change the (intended) framework interface.
• This PR adds methods or properties to the framework interface.
• This PR removes or renames methods or properties in the framework interface.

[bdistin]

[PyroTechniac]

Looked through it a second time and found a few things

[PyroTechniac]

LGTM

[kyranet]

Superseded by #916 to move the base branch into this repository.