SAN FRANCISCO — Add another name to the list of progressive Democrats seriously considering a primary challenge to California’s senior Senator Dianne Feinstein: wealthy financial entrepreneur Joseph N. Sanberg. Sanberg, 38 — co-founder of Aspiration.com, a socially-conscious investment firm, and a founding investor in Blue Apron, the home delivery meal service — has burnished his progressive credentials in recent years by successfully lobbying for the creation of CalEITC4Me, the earned income tax credit program which he’s advocated as a means of delivering economic relief to low-income families.