#1589 Add 'cache_prompt' for l.cpp

public/scripts/textgen-settings.js

@@ -769,6 +769,7 @@ export function getTextGenGenerationData(finalPrompt, maxTokens, isImpersonate,
             'logit_bias': logitBiasArray,
             // Conflicts with ooba's grammar_string
             'grammar': settings.grammar_string,
+            'cache_prompt': true,
         };
         params = Object.assign(params, llamaCppParams);
     }