feat: add Apps endpoint and query parameter support

- add `Apps` endpoint to the `Client` struct and initialize it in
`NewClient`
- implement `doWithJsonResponse` helper to handle request execution and
JSON decoding in one step
- update `newRequest` to support passing and encoding query parameters
via `net/url`
- rename `Option` to `ClientOption` for better clarity in the
`NewClient` signature
- refactor `Ping` tests to use a more structured nested layout
- remove `option.go` and `option_test.go` as part of the configuration
refactor

ping.go

@@ -36,7 +36,7 @@ type PingEndpoint struct {
 //	    log.Fatal("Ping failed:", err)
 //	}
 func (p *PingEndpoint) Get(ctx context.Context) error {
-	req, err := p.client.newRequest(ctx, http.MethodGet, pingPath, nil)
+	req, err := p.client.newRequest(ctx, http.MethodGet, pingPath, nil, nil)
 
 	if err != nil {
 		return err