Cfn-lint

Features
- Standard cfn-lint Errors ([E0000](https://github.com/aws-cloudformation/cfn-python-lint/blob/main/docs/rules.md#E0000)) for null, duplicate, and parse errors
- Add a new check for CloudFormation limits
- Add a new check for Parameter, Resource, Output, and Mapping names
- Update specs to those released on May 25th, 2018
- Strong type checking for property values result in Errors ([E3012](https://github.com/aws-cloudformation/cfn-python-lint/blob/main/docs/rules.md#E3012))
Fixes
- Transform logic updated to not add a Role if one is specified for a serverless function
- Fixed logic around Fn::If when the result is an object
- Fix conditions when checking property value structure

Features
- Update CloudFormation specs to include recent releases
- Add checks for duplicate resource names
- Add checks for null values in templates
- Add support in Circular Dependency checks to go multiple levels deep
- Add check for unused mappings
- Add check for unused and not found conditions
- Convert Errors to Warnings that don't cause a failure when implementing a template
Fixes
- Fix check for cfn-lint configurations in templates
- Fix Sub Functions checks failing on sub stacks or custom resources
- Fix Serverless Transforms not failing when trying to create multiple RestApiIds
- Fix TOX encoding issues with certain JSON files
- Update Lambda Memory size to 3008
- Fix FindInMap failing when the first parameter is also FindInMap
- Fix key search function to appropriately respond to nested finds (FindInMap inside a FindInMap)

Features
- Capability to merge and modify the CloudFormation spec with provided JSON
- Allows for changing what properties are required
- Can change what resource types are allowed
- Remove warnings that were in error checks to keep errors focused on issues preventing success
- Improve circular dependency checks to go multiple levels deep
- Check null and duplicate values in JSON and YAML templates
Fixes
- Some primitive type properties were not getting checked
- Include support for Long as a number based check
- Improve get condition values to support more complex scenarios

Features
- Added a rule to check for only one resource property in a set
- Added a rule for more than one of resource properties in a set
- Added a rule for mutually exclusive resource properties

Fixes
- Support parsing JSON files that have tabs
- Better error handling for when a property is a list instead of an object
- Error handling for when files can't be read or don't exist

Features
- Fix for supporting more parameter types when checking REFs to parameters for Security Groups

Features
- Exit code non zero on errors or warnings