[Feat] Create semester model

[Aastha-S-Rai]

Description

Create a file semester.js in models folder
Add schema with required key and value pairs

Proposed Solution

number: int ENUM: [1..8]  
type: virtual ENUM: [Odd, Even]
academicYear: str 
startDate: Date
endDate: Date

[deepti-50]

Assign this issue to me

[TejasNair9977]

closed in #324