Implemented API endpoint for getting employee count ranges

[banders]

Description

Added a new API endpoint to get employee count ranges (/api/v1/codes/employee-count-ranges). The new endpoint requires users to be authenticated and expects a valid "frontend token" in the HTTP Authorization header.

The new API endpoint is defined in src/v1/routes/code-routes.ts. It is suggested that the same file be used to define other endpoints used to access static content (such as NAICS codes).

"Under the hood" the implementation of the new API endpoint makes a query to the database table pay_transparency.employee_count_range. The PR includes a database migration to insert preliminary data into this table.

Fixes # (issue)

Type of change

Please delete options that are not relevant.

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• New unit test (in code-service.spec.ts) for new function codeService.getAllEmployeeCountRanges()
• New unit test (in app.spec.ts) for the API endpoint itself

Checklist

• I have read the CONTRIBUTING doc
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have already been accepted and merged

[sonarcloud]

[Pay Transparency Backend] Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

92.9% Coverage
0.0% Duplication

The version of Java (11.0.17) you have used to run this analysis is deprecated and we will stop accepting it soon. Please update to at least Java 17.
Read more here

[sonarcloud]

[Pay Transparency Frontend] Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
No Duplication information

The version of Java (11.0.17) you have used to run this analysis is deprecated and we will stop accepting it soon. Please update to at least Java 17.
Read more here