🎚️ feat: Custom Parameters (#7342)

* #

* - refactor: simplified getCustomConfig func

* #

* - feature: persist values for parameters with optionType of custom

* #

* - refactor: moved `Parameters/settings.ts` into `data-provider` so that both frontend and backend code can use it.

* - feature: loadCustomConfig can now parse and validate customParams property for `endpoints.custom` in `librechat.yaml`

* # fixed linter

* # removed .strict() in config.ts

* change: added packages/data-provider/src to SOURCE_DIRS for i18n check

* # removed unnecessary lodash imports

* # addressed PR comments
# fixed lint for updated files

* # better import for lodash (w/o relying on tree-shaking)

packages/data-provider/src/config.ts

@@ -279,6 +279,12 @@ export const endpointSchema = baseEndpointSchema.merge(
     headers: z.record(z.any()).optional(),
     addParams: z.record(z.any()).optional(),
     dropParams: z.array(z.string()).optional(),
+    customParams: z
+      .object({
+        defaultParamsEndpoint: z.string().default('custom'),
+        paramDefinitions: z.array(z.record(z.any())).optional(),
+      })
+      .strict(),
     customOrder: z.number().optional(),
     directEndpoint: z.boolean().optional(),
     titleMessageRole: z.string().optional(),