The senator who most consistently has opposed President Donald Trump’s appointees is not a famous liberal firebrand like Bernie Sanders (I-Vt.) Elizabeth Warren (D-Mass.), Al Franken (D-Minn.) or Chuck Schumer (D-N.Y.). Instead, it is New York’s junior Democratic senator, Kirsten Gillibrand, who took office in 2009 with a reputation as a moderate after two years in…