Add missing fields to Project-related structs
Add missing fields to Project-related structs

Adds the following fields:
- AnalyticsAccessLevel (Project, CreateProjectOptions, EditProjectOptions)
- KeepLatestArtifact (Project, EditProjectOptions)
- MergePipelinesEnabled (Project, CreateProjectOptions, EditProjectOptions)
- MergeTrainsEnabled (Project, CreateProjectOptions, EditProjectOptions)
- RestrictUserDefinedVariables (Project, EditProjectOptions)
- MergeCommitTemplate (Project, CreateProjectOptions, EditProjectOptions)
- SquashCommitTemplate (Project, CreateProjectOptions, EditProjectOptions)

xanzy/go-gitlab