feat: encrypt private keys saved on disk and in database (#682)

Co-authored-by: Kyle Mendell <kmendell@ofkm.us>

backend/internal/utils/testing/round_tripper.go

@@ -0,0 +1,38 @@
+// This file is only imported by unit tests
+
+package testing
+
+import (
+	"io"
+	"net/http"
+	"strings"
+
+	_ "github.com/golang-migrate/migrate/v4/source/file"
+)
+
+// MockRoundTripper is a custom http.RoundTripper that returns responses based on the URL
+type MockRoundTripper struct {
+	Err       error
+	Responses map[string]*http.Response
+}
+
+// RoundTrip implements the http.RoundTripper interface
+func (m *MockRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
+	// Check if we have a specific response for this URL
+	for url, resp := range m.Responses {
+		if req.URL.String() == url {
+			return resp, nil
+		}
+	}
+
+	return NewMockResponse(http.StatusNotFound, ""), nil
+}
+
+// NewMockResponse creates an http.Response with the given status code and body
+func NewMockResponse(statusCode int, body string) *http.Response {
+	return &http.Response{
+		StatusCode: statusCode,
+		Body:       io.NopCloser(strings.NewReader(body)),
+		Header:     make(http.Header),
+	}
+}