59867 Replace ANDROID_HOME user messages with ANDROID_SDK_ROOT (cla: yes, platform-android, team, tool, waiting for tree to go green)

59874 Parse build ios framework build mode from params (a: existing-apps, cla: yes, platform-ios, tool, waiting for tree to go green)

59896 gitignore .last_build_id file in the repo (cla: yes, d: examples, team, tool, waiting for tree to go green)

59907 port devicelab from idevice_id -> xcdevices (cla: yes, team, tool)

59996 [flutter_tools] android test cleanups (cla: yes, tool, waiting for tree to go green)

59997 [flutter_tools] cleanup fuchsia tests (cla: yes, tool, waiting for tree to go green)