add CAM and VAM references

[submodule "cdd"]

	path = cdd

	url = https://forge.etsi.org/rep/ITS/asn1/cdd_ts102894_2.git

[submodule "cam"]

	path = cam

	url = https://forge.etsi.org/rep/ITS/asn1/cam_en302637_2.git

[submodule "vam"]

	path = vam

	url = https://forge.etsi.org/rep/ITS/asn1/vam-ts103300_3.git

To compile the module, the following modules are required:

- The **[ITS-Container](https://forge.etsi.org/rep/ITS/asn1/cdd_ts102894_2)** module from the [ETSI TS 102 894-2 v1.3.1](https://www.etsi.org/deliver/etsi_ts/102800_102899/10289402/01.03.01_60/ts_10289402v010301p.pdf) - Common Data Dictionary

- **[CAM-PDU-Descriptions](https://forge.etsi.org/rep/ITS/asn1/cam_ts302637_2)** module from [ETSI EN 302 637-2 v1.4.1](https://www.etsi.org/deliver/etsi_en/302600_302699/30263702/01.04.01_60/en_30263702v010401p.pdf) - Cooperative Awareness Service

- **[ITS-Container](https://forge.etsi.org/rep/ITS/asn1/cdd_ts102894_2)** module from [ETSI TS 102 894-2 v1.3.1](https://www.etsi.org/deliver/etsi_ts/102800_102899/10289402/01.03.01_60/ts_10289402v010301p.pdf) - Common Data Dictionary

The module requires temporary reference to VAM-Temp-Imports definitions until the imported Data Elements will be integrated in CDD:

- **[VAM-Temp-Imports](https://forge.etsi.org/rep/ITS/asn1/vam-ts103300_3/blob/master/VAM-Temp-Imports.asn)** module from [ETSI TS 103 300-3 v2.1.1](https://www.etsi.org/deliver/etsi_ts/103300_103399/10330003/02.01.01_60/ts_10330003v020101p.pdf) - VRU Awareness Message

Subproject commit fed28cfe5c930dd9d3109ff1162c28008697754a

Subproject commit aa7e1dfaf471fa9f464baa26f525f54866e0acd2