Pycfmodel

Additions
- Added `all_statement_conditions` property to `Resource`. This enables a list of all IAM Conditions defined in a Resource to be captured and used.

Additions
- `Resource` class is able to run `policy_documents` when it's not a mapped resource and return a valid list of `OptionallyNamedPolicyDocument`.
- Update `CLOUDFORMATION_ACTIONS`.

Additions
- Added `Principal` property.
- Modified `Statement` property to work with `Principal` property
- Added `Generic` property. Any property under this class will be cast to an existing model of `pycfmodel` if possible.
- Modified `GenericResource`, `ESDomainProperties`, `OpenSearchDomainProperties` and `S3BucketProperties` to work with `Generic` property
- Update `CLOUDFORMATION_ACTIONS`

Additions
- Added `ESDomain` resource.
- Added `OpenSearchDomain` resource.
- Update `CLOUDFORMATION_ACTIONS`

Fixes
- `Transform` field of a CloudFormation template can now correctly handle both string and list of strings (see: https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/transform-section-structure.html)
- Support the usage of `aws:sourceVpce` in `IpAddress` conditions. When comparing conditions however, `pycfmodel` will block any comparison with something that is not an IPv4 or IPv6 address.

Additions
- Update `CLOUDFORMATION_ACTIONS`.

Additions
- Update `CLOUDFORMATION_ACTIONS`.
- Add documentation regarding missing IAM actions.