fix fields query in transactions

[cfaur09]

Reasoning

• related with reported bug from community : [Bug]: Wrong call when multiple fields are applied on "Transactions" #1396
• the values from fields query were not serialized so when the query was added, the URL was build as follow: fields=txHash&fields=code

Proposed Changes

• add explode:false ApiQuery property to make sure that the values are serialized

How to test

• go to local swagger
• on transactions controller, add multiple values to fields API Query and the result should not return 500 InternalServer Error

[github-actions]

k6 load testing comparison.
Base Commit Hash: 9638379
Target Commit Hash: 6ba7465

Metric	Base				Target				Diff
	Avg	Max	90	95	Avg	Max	90	95	Avg	Max	90	95
Nodes	45.43	590.89	48.83	50.41	51.11	658.92	55.52	57.56	+12.49% 🔴	+11.51% 🔴	+13.69% 🔴	+14.18% 🔴
Accounts	46.02	864.80	48.81	50.46	51.86	1247.66	55.55	57.54	+12.69% 🔴	+44.27% 🔴	+13.81% 🔴	+14.02% 🔴
Mex	45.05	317.53	48.82	50.44	50.58	540.41	55.51	57.56	+12.27% 🔴	+70.19% 🔴	+13.69% 🔴	+14.12% 🔴
Pool	45.57	486.24	48.86	50.41	51.06	691.61	55.55	57.56	+12.03% 🔴	+42.24% 🔴	+13.71% 🔴	+14.18% 🔴
Tokens	45.62	578.01	48.84	50.41	50.74	420.56	55.50	57.55	+11.23% 🔴	-27.24% ✅	+13.65% 🔴	+14.15% 🔴
Blocks	50.68	1167.39	49.18	51.46	56.98	990.63	55.95	59.53	+12.43% 🔴	-15.14% ✅	+13.75% 🔴	+15.68% 🔴
Transactions	57.05	1631.89	49.55	51.48	65.17	2352.09	56.28	60.30	+14.24% 🔴	+44.13% 🔴	+13.59% 🔴	+17.12% 🔴
Test Run Duration	60002.13				60004.17

Legend: Avg - Average Response Time, Max - Maximum Response Time, 90 - 90th Percentile, 95 - 95th Percentile
All times are in milliseconds.