Implement /random_string command

[tanamaroby]

Issue Title: Implement /random_string Command

Issue Description: As a user of our Discord bot, I want to be able to use a "/random_string" command to generate a random string of characters based on a given length, so that I can use it for various purposes within Discord.

Feature Description:

• The "/random_string" command should take one argument, which is a number representing the desired length of the random string.
• When invoked, the bot should generate a random string of characters with the specified length.
• The characters in the random string should include alphanumeric characters and special symbols.
• The bot's response should include the generated random string.

Acceptance Criteria:

• The "/random_string" command is successfully implemented and tested.
• Invoking the "/random_string" command with a valid number argument should result in the bot generating and displaying a random string of characters with the specified length.
• The bot's response should include the generated random string.

Additional Notes:

• This feature will provide users with a way to generate random strings for various purposes within Discord.
• Please ensure thorough testing of the "/random_string" command functionality before closing this issue.