Contains the following minor improvements to the block entities migration:
* The migration won't be stopped anymore if it can't read a template file.
* The migration will exit early if a template doesn't contain the two characters we need to migrate.
* Reduced the amount of code that is wrapped by a try/catch to avoid suppressing errors.
PR Close#52209
#51891 introduces a new syntax that assigns a new meaning to the `@` and `}` in Angular templates. This is problematic for existing apps which may have the characters in their templates already, because it can lead to syntax errors.
These changes add an `ng update` schematic that will replace any usages of the special characters with their HTML entities.
PR Close#51905