Implement backend for admin profile image management

[Madhawa97]

Description:
Implement backend functionality to support admin in setting or changing profile images for mentors.

Tasks:

• Create or update API endpoints for image upload and update.
• Implement authorization checks for admin actions.

Acceptance Criteria:

• Develop/ update API endpoints for uploading and updating mentor profile images
• Implement authorization checks to ensure only admins can change images

Additional Information:
Later:

• Implement notification system for informing mentors of image changes.

Related Dependencies or References:

[anjula-sack]

@Disura-Randunu Would you like to work on this?

[Disura-Randunu]

@Disura-Randunu Would you like to work on this?

@anjula-sack sure. Will work on this

[Disura-Randunu]

@anjula-sack this was implmented as part of #169
We can use "PUT /api/mentor" and just provide only the image under "profile_image" property in form data to update the mentor profile image without other details.

Should I make a seperate endpoint just for updating the mentor profile image as well?