feat: made some external link URLs configurable

[banders]

Description

Inject new config properties into frontend for several external URLs. Update landing page and dashboard to use the injected URLs.

Fixes # GEO-632

Type of change

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

How Has This Been Tested?

Visual inspection in the running application

Checklist

• 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

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[sonarqubecloud]

Quality Gate passed for 'Pay Transparency backend-external'

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
No data about Duplication

See analysis details on SonarCloud

[sonarqubecloud]

Quality Gate passed for 'Pay Transparency Backend'

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
No data about Duplication

See analysis details on SonarCloud

[sonarqubecloud]

Quality Gate passed for 'Pay Transparency Frontend'

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
87.5% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[sonarqubecloud]

Quality Gate passed for 'Pay Transparency doc-gen-service'

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
No data about Duplication

See analysis details on SonarCloud