[Feature] Custom fields for all objects

[echo6ix]

Implement the ability for administrators to create custom fields for objects (scenes, studios, tags, performers). This will allow for flexible customization, mitigate requests for specific fields, and let different installations of stash-box tailor themselves to their niche.

Why This is Useful

• Avoids hardcoding specific fields, making the app more adaptable.
• Allows customization based on administrative/community preferences without requiring developer to implement a new field
• Mitigates frequent requests for adding various specific fields.
• We don't always think of the fields we need in the present for what may be useful in the future, and considering developer resources may be very limited it would be easy for the administrator to create custom field

Custom Field Types

Custom fields would have a set type of definable field values for an administrative to choose from:

• Multi field values
• Integer
• Date
• Select/Lookup (pulls data from database in dropdown select field. Admin would select which fields to reference from a predefined list "Performer name", "Studio name", etc)
• List (with predefined values)
• Images (with definable limitations, such as aspect ratio, size, and resolution)
• Strings

Related issues

• [Feature] Add more info fields to studios #676
• [Feature] Performer tags #790
• [Feature] Add Alias or Scene code field to StashDB for studios #707
• [Feature] Alternate Titles #345
• [Feature] Production Dates #346
• [Feature] dvd cover art archive  #334
• [RFC] Performer Image Categorization #237
• [Feature] Add penis size, for male and trans performers #206
• [Feature] Add performer shoe size #205
• [Feature] Performer death date #204
• [RFC] Release Groups / Scene Groups #663