test: rename _fixtures to __fixtures__

.eslintignore

.prettierignore

test/config/cli.spec.ts

test/config/config/__fixtures__/argv.ts

test/config/config/__fixtures__/file.js

test/config/config/__fixtures__/file2.js

test/config/decrypt.spec.ts

test/config/file.spec.ts

test/config/index.spec.ts

test/config/keys/__fixtures__/private.pem

test/config/npm/__fixtures__/01.json

test/config/npm/__fixtures__/02.json

test/config/npm/__fixtures__/coffeelint.json

test/config/npm/__fixtures__/next.json

test/config/npm/__fixtures__/typescript.json

test/config/npm/__fixtures__/vue-test-utils.json

test/config/npm/__fixtures__/vue.json

test/config/npm/__fixtures__/webpack.json

test/platform/bitbucket-server/__fixtures__/responses.ts

test/platform/bitbucket-server/index.spec.ts