[Feature] Generator replacement holders insertion

[Durtur]

Generator settings page, when editing creature / namesets.

• Anywhere in the text it is possible to insert replacement placeholders, such as for prewritten value tables and gender dependant pronouns for extra randomization.
• Currently, the user cannot possibly be aware of it since it's hidden in the code.
• Provide some means for the user to see these replacement values or insert them.
• These values are located in the huge names.json file, replacement_values