Add custom generator to custom text modal

[Miodec]

Add a new button to custom text modal that works simillarly to words filter:

• opens a new modal
• modal contains:
  • input box of strings separated by spaces (can be characters, bigrams, whatever)
  • maybe provide some presets? like alphas, numbers, specials, bigrams, trigrams.
  • min word length (input type number or slider?)
  • max word length
  • set and add buttons
• it will generate words by randomly picking from the strings until a max word length is reached
• then set or append the custom text, just like words filter

Discussed in #6938

[VMadhav007]

Hey , i am ready to work on this