[IMP] Add image type enum and property in image_data

[lasley]

• Add an enum for the image types. Currently mapped are the distinct values from an existing prod, with the one known value filled (prescription). Pending response from CP on others
• Add image_type computed property in image_data that maps the type code using the enum

[codecov]

Codecov Report

Merging #40 into master will increase coverage by 0.01%.
The diff coverage is 100%.

@@ Coverage Diff @@## master #40 +/- ##
=========================================
+ Coverage 97.68% 97.7% +0.01% 
=========================================
Files 60 61 +1 Lines 1598 1610 +12 Branches 42 42 =========================================
+ Hits 1561 1573 +12 
Misses 20 20 Partials 17 17

Impacted Files	Coverage Δ
carepoint/models/cph/image_data.py	100% <100%> (ø)	⬆️
carepoint/models/enum_image_type.py	100% <100%> (ø)

[lasley]

To get the current list of these you can use the SQL below in the CPH database

select * from csct where ct_id = 420 (This will let you know that the CT_ID of 420 refers to image types.)
select * from csct_code where ct_id = 420 (The list of image types is defined in the csct_code table using the Code_num which you have below)

Example: Code of 2 in my database signifies an image listed as an RX.