Add project_ to _security_attribute table

Gal Katzrequested to merge
gkatz_add_attributes_to_project_table into master

What does this MR do and why?

Adds project_to_security_attributes connection table that hold connection between Project and its Security::Attributes, together with some metadata.

See [Backend] Security attributes implementation plan (#554843 - closed) • Gal Katz • 18.5

Changelog: added

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Related to Add many to many connection table between proje... (#556694 - closed) • Gal Katz • 18.4

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