Updated test to make new output of Type mismatch errors
Update usage of isInstanceOf to TypeMatcher

Closes #842 

See https://github.com/dart-lang/sdk/issues/33388

The latest version of `stream_channel` made the type explicit on the
method signature whereas before it was implicit with an `as` cast inside
the method. Most clients wouldn't be impacted is but this package is
because of it's use of `implicit-casts: false`.

We no longer use `mapMap` so the hints aren't printed. Fix the tests to
allow for the "Compiled" message from dart2js. Update the reason for
skipping one test which has an incorrect line number - we will need to
investigate why this line is wrong.

Allow Matcher usage in the `_print` call since the "Compiled" message is
unpredictable.

Follow-up to https://github.com/dart-lang/test/pull/869

Searched for lines matching `var \w+;`. This is a much weaker version of
no-implicit-dynamic. This catches a bunch of places where we otherwise
had dynamic calls and tightens up types a bit. Where we are relying on
being able to parse to multiple types and then throw a specific
excpetion or return null on bad types I added an explicit `dynamic`.

This isn't something we _can_ fix because user specific (json serializable) types can be sent across the channel.

- Fix syntax for upgrading errors in the analysis options
- Ignore todo hints since they are very noisy
- Enable check for implicit casts
- Fix a bunch of implicit casts in the test directory

More towards #842

- Export @Retry annotation (this is technically broken now but the corresponding tests only fail under preview-dart-2)
- Fix type issue with mapping over dynamic values

There are still errors in tests which may be harder to fix so we can't
check in the change to analysis options.

This should make it easier to diagnose Dart 2 semantic issues as more of
the places where there can be failures are explicit.

Most of the changes are just adding explicit `as` statements and keeping
the semantics that already existed. In a few places an uninitialized
`var` is given a type, and in others a reused variable name with
different types is split into multiple variables.

The changes in the frontend code are the most risky, since some users
might still be using that code in a non Dart 2 runtime and relying on
looseness which is lost with an explicit cast.

Pin to the dev.60 SDK for now since there are failures on the newer SDK.

The typedef was misused to mean either `Function` or `Function()` in
various places and worked because the difference was not checked. The
doc comment was also incorrect because there were places it was used
where a return value was explicitly necessary. Replace with an inline
function type definition using the appropriate choice for the location.

Where possible also replace with Function types that flow through the
required return types.

* add root_line, root_column, and root_package_url to the json reporter

* update docs, pubspec, changelog

* enable the compact reporter and colors on windows, if stdout.supportsAnsiEscapes == true

* update pubspec/changelog, code review updates

We no longer support an SDK old enough that any of the referenced issues
are still a problem.

```
type 'WebSocketChannel' is not a subtype of type 'StreamChannel<String>' of 'channel'
```

Cast the `WebSocketChannel` to indicate that all values in each
direction will be `String`.

```
type 'CloseGuaranteeChannel<dynamic>' is not a subtype of type 'VirtualChannel'
```

Avoid using the `suiteChannel` variable for two types. It needs to start
as a `VirtualChannel` which has the `id` field, and then later be a
`StreamChannel`.

```
type 'RunnerSuite' is not a subtype of type 'FutureOr<Future<RunnerSuite>>'
```

Avoid the attempted Future flattening which was never correct but was
supported in the Dart 1 VM.

Fixes #840

Invoke a non-existing method after casting an object to `dynamic` to get
the behavior.

Prepare to release 0.12.38+1

- added `// ignore` comments for references to internal deprecated members
- removed comments referencing deprecated arguments
- upped args minimum constraint and migrated to `addMultiOption`
- dropped polymer support
- added `--fatal-infos` and `--fatal-warnings` to dartanalyzer test to prevent regressions and expose new warnings via cron jobs.
- fixed up some markdown issues

Closes #824

Makes test/frontend/never_called_test work with --preview-dart-2