evas: add pattern "style" when evas query fonts via fontconfig

evas: add pattern "style" when evas query fonts via fontconfig

Summary:
Some fonts can have weird style and weight value.
If a font has a style name as "medium" and a weight value as "semi-bold",
Evas can't load the font using "font=Somefont:style=Medium".
It only can be load with "font=Somefont:style=SemiBold" or
"font=Somefont:weight=SemiBold".
On the other hand, it could be loaded when I tested the following commands.
fc-match -s ":family=Somefont:style=Medium" or
fc-match -s ":family=Somefont:weight=SemiBold"

Evas also should load font based on font's style name.
@fix

Test Plan: N/A

Reviewers: tasn, herdsman, cedric, woohyun, raster

Reviewed By: raster

Subscribers: Blackmole, z-wony, jpeg

Differential Revision: https://phab.enlightenment.org/D4108

Change-Id: Ibd9f53cb62568e2ee6e1e627f75607936396e6ff