[skip-changelog] Migrate tests from test_board.py to board_test.go (#1847)

* Migrated TestBoardList from test_board.py to board_test.go

* Migrated TestBoardListWithInvalidDiscovery from test_board.py to board_test.go

* Migrated TestBoardListall from test_board.py to board_test.go

* Migrated TestBoardListallWithManuallyInstalledPlatform from test_board.py to board_test.go

* Migrated TestBoardDetails from test_board.py to board_test.go

* Migrated TestBoardDetailsNoFlags from test_board.py to board_test.go

* Migrated TestBoardDetailsListProgrammersWithoutFlags from test_board.py to board_test.go

* Migrated TestBoardDetailsListProgrammersFlags from test_board.py to board_test.go

* Migrated TestBoardSearch from test_board.py to board_test.go

* Migrated TestBoardAttachWithoutSketchJson from test_board.py to board_test.go

* Migrated TestBoardSearchWithOutdatedCore to board_test.go and deleted test_board.py

Author: MatteoPologruto