Consider moving `cwe` directory into `vuln-list-nvd`

[simar7]

Today AVD uses NVD updates to construct its pages therefore in the past it had to clone vuln-list. It only uses the nvd dir (now part of vuln-list-nvd and cwe directory (still part of vuln-list) to build content.

Today vuln-list still has the nvd directory inside of it (2mo old as of writing this) and in addition AVD will have to clone the vuln-list-nvd repo which again has NVD definitions.

Can we move the cwe into the vuln-list-nvd repo as well so AVD has to clone smaller repo (only vuln-list-nvd) and can potentially reduce its runtime by doing so?