Allow all ajv option

[kingdun3284]

Allow all ajv option

[LoicPoullain]

Hi @kingdun3284 👋

I'd rather not to go with the solution that takes an object from the config and pass it to AJV.

I admit it's (really) annoying to add every property every time but this way has some advantages through:

• the types of the config values are properly checked by Foal before passing them to AJV;
• people willing to use .env files for the configuration can do so (with keys such as "allErrors: env(SETTINGS_AJV_ALL_ERRORS) for example)
• if a type coercion is needed, Foal will handle it. For example, the values "true" will properly be converted to true (this type of situation often occurs with environment variables)
• as of today, the config system assumes that the values of the config are primitives types. Even if passing an object might work, this is a behavior that could break in the future.