Sampling: Add additive param to overrides

Additive is used to add collections together. Currently, it's used
for lists, but it can be used for dictionaries in the future.

Signed-off-by: kingbri <bdashore3@proton.me>

sampler_overrides/sample_preset.yml

@@ -14,6 +14,7 @@ max_tokens:
 stop:
   override: []
   force: false
+  additive: false
 token_healing:
   override: false
   force: false
@@ -104,6 +105,7 @@ ban_eos_token:
 logit_bias:
   override:
   force: false
+  additive: false
 
 # MARK: CFG scale
 cfg_scale: