LP#1614807: Holds history should look like other My Account screens

LP#1614807: Holds history should look like other My Account screens

The Holds History My Account interface looks entirely different than the Items
Out, Check Out History, and Items On Holds interfaces. This commit adds a new
acct_holds_hist_header CSS class that shares the same styles as the CSS classes
used for the other three interfaces. Inline styles are removed from this table.

Test plan
Pre-patch: Go to the My Account Items Out, Check Out History, Items on Hold,
and Holds History interfaces. While the first three interfaces use a table with
a white background for the headers and a gray background for the body, the Holds
History interface is the opposite.

Post patch: All four interfaces should show a similar style to each other.

Signed-off-by: Kathy Lussier <klussier@masslnc.org>