Well, all the easy ones, anyway.

For some reason `// ignore:` isn't working for me so I've disabled
lints that need that. Also disabled those that require a ton of work
(which I'm doing, but not in this PR, to keep it reviewable).

This adds:
- avoid_init_to_null
- library_names
- package_api_docs
- package_names
- package_prefixed_library_names
- prefer_is_not_empty
- sort_constructors_first
- sort_unnamed_constructors_first
- unnecessary_getters_setters

After this patch, the flutter logs command on Android shows only log messages
since the command was run. Previously, it showed historical logs, which was
confusing.

Fixes #2013

flutter start's method of finding devices to run the app on is not suitable for flutter drive.

This commit also refactors several tool services to allow mocking in unit tests.

This provides a fast way to iterate on changes to a Flutter app that only
involve updates to Dart code and do not require a full build and install
of the FLX and APK

remove the device factory methods as well as the device cache

Add a --full-restart flag to the start command that controls whether we stop the application process

SkyActivity now allows reloading application Dart code within an existing
activity.  If a SkyActivity instance is already running, then passing
--no-full-restart will restart the Dart code without killing and restarting
the SkyShell application.
(full-restart will remain the default until the engine
that supports this is rolled out)

Also remove the obsolete --poke flag

rename to printTrace(), printStatus(), and printError()

Also fix a bug where the trace command may capture the wrong file
if multiple trace file paths are in the Android log buffer.

Previously we found a lower bound timestamp for the trace path log
by running the date command on the device and parsing the result on
the host.  This could yield an inaccurate result if the device and
host are using different time zones.

The command will now obtain the most recent timestamp in the device's
time format by running logcat.

remove device type specific checks