feat(managers/custom): generic manager for json files (#32784)

docs/usage/configuration-options.md

lib/config/options/index.ts

lib/config/validation-helpers/utils.ts

lib/config/validation.spec.ts

lib/config/validation.ts

lib/modules/manager/custom/api.ts

lib/modules/manager/custom/index.spec.ts

lib/modules/manager/custom/jsonata/index.spec.ts

lib/modules/manager/custom/jsonata/index.ts

lib/modules/manager/custom/jsonata/readme.md

lib/modules/manager/custom/jsonata/schema.ts

lib/modules/manager/custom/jsonata/types.ts

lib/modules/manager/custom/jsonata/utils.ts

lib/modules/manager/custom/types.ts