opt: don't focus on the main window if word comes from headword dialog

fix https://github.com/xiaoyifang/goldendict-ng/issues/1323

Note that this focus stealing exists for a decade. Honestly cannot tell if it is a feature or misdesign 😅

As of now, I think it is a misdesign, because the dialog is a tall narrow window, it don't cover the article display area (probably only because today's computer monitor is larger than a decade ago).

https://github.com/xiaoyifang/goldendict-ng/commit/46298a842cead991e271535105db546f80f88eba#diff-5672b26c3952a17c577362e80c313b2d937da7cdf2d4e4a91bba90e68ed855ccR3513

Related change

Move headwordReceived into lambda, because it only serves the head word dialog.
Stop the confusing toggle**** and showOnly thing

xiaoyifang / goldendict-ng

opt: don't focus on the main window if word comes from headword dialog #1933

Quality Gate passed