Refactor capital fund category from enum to check constraint

[TangoYankee]

Acceptance criteria

• Remove the captial_fund_category enum
• Change the type of the capitalFundCategory field of the capital_project_fund table from an enum to text
• Add the check contraint to the capitalFundCategory field of the capital_project_fund table
• Change the type of the category field of the capital_commitment_fund table from an enum to text
• Add the check contraint to the type of the category field of the capital_commitment_fund table
• Regenerate the migration

Related

Depends on: #386