fix(input): by default, do not trim input[type=password] values

Previously, all input types using ngModel and textInputType() would trim
values if the ng-trim attribute was unspecified. This is undesirable for
passwords because a user's input should always be canonical in that case.

This CL changes this behaviour by only trimming by-default if the input type
is not password. In the future, if other input types need to be checked, or if
the input type needs to be checked at runtime, this may be refactored to
support those cases.

BREAKING CHANGE:

Previously, input[type=password] would trim values by default. This is no
longer the case, and requires an explicit `ng-trim="value other than 'false'"`
to ensure that the value is trimmed in casees where this is actually
desirable.

Example:

```html
<input type="password" ng-model="password"> <!-- WILL NOT TRIM VALUE -->
<input type="password" ng-model="password" ng-trim="false"> <!-- WILL NOT TRIM VALUE -->
<input type="password" ng-model="password" ng-trim="ANYTHING ELSE"> <!-- WILL TRIM VALUE -->
```

Closes #8230