Adds fixture tests

[technobly]

• Adds more fixture tests
• Updates some exiting fixture tests

Current state

• All tests passing ✅

Pass/Fail    Fixture Tests
                └── wiring
                    ├── ble_central_peripheral
Pass                │    ├── bw_1.config.js - Argon/Argon
Pass                │    └── bw_2.config.js - Photon2/Photon2
                    ├── ble_scanner_broadcaster
Pass                │    ├── bw_1.config.js - Argon/Argon
Pass                │    └── bw_2.config.js - Photon2/Photon2
                    ├── i2c_master_slave
Pass                │    ├── bw_1.config.js - Argon Master / Photon2 Slave
Pass                │    ├── bw_2.config.js - Photon2 Master / Argon Slave
Pass                │    ├── bw_3.config.js - Argon Master / Argon Slave
Pass                │    └── bw_4.config.js - Photon2 Master / Photon2 Slave
                    ├── i2c_mcp23017
Pass                │    ├── bw_1.config.js - Argon
Pass                │    └── bw_2.config.js - Photon2
                    ├── serial_loopback
Pass                │    ├── bw_1.config.js - Photon2
Pass                │    └── bw_2.config.js - Argon
                    ├── serial_loopback2
Pass                │    ├── bw_1.config.js - Photon2
Pass                │    └── bw_2.config.js - Argon
                    ├── sleep20
Pass                │    ├── bw_1.config.js - Argon Tester / Photon2 Device
Pass                │    └── bw_2.config.js - Photon2 Tester / Argon Device
                    └── spi_master_slave
Pass                     ├── bw_1.config.js - Photon2 SPI Master / Argon SPI1 Slave
Pass                     ├── bw_2.config.js - Argon SPI Master / Argon SPI1 Slave
Pass                     └── bw_3.config.js - Photon2 SPI1 Master / Photon2 SPI1 Slave

[XuGuohui]

1. ble_central_peripheral:
   • Argon: ✅
   • Photon2: ✅
   • Argon/Photon2: ✅
2. ble_scanner_broadcaster:
   • Argon: ✅
   • Photon2: ✅
3. serial_loopback:
   • Argon: ✅
   • Photon: ✅
4. serial_loopback2:
   • Argon: ✅
   • Photon2: ✅
5. i2c_master_slave:
   • Argon: Failed occasionally (figured out)
   • Photon2: Failed if re-run the test without hard reset (in progress)
6. spi_master_slave: TODO