'Add Selection To Next Find Match' ignores 'editor.wordSeparators' setting

[pedzed]

VS Code version: Code 1.37.1 (f06011a, 2019-08-15T16:17:25.463Z)
OS version: Linux x64 4.15.0-55-generic snap

Steps to Reproduce:

1. Double click a word preceded by a dollar (e.g. $myVariable).
2. Expect: myVariable to be selected with the default editor.wordSeparators setting.
3. Use the keyboard shortcut of 'Add Selection To Next Find Match' on the same word to do the same thing.
4. Expect: myVariable to be selected with the default editor.wordSeparators setting.

The first test passes. The second does not. editor.wordSeparators seems to be ignored for the 'Add Selection To Next Find Match' feature.

Default editor.wordSeperators for reference:

"editor.wordSeparators": "`~!@#$%^&*()-=+[{]}\\|;:'\",.<>/?",

Removing the dollar character results in having $myVariable selected rather than myVariable on a double click (which is as expected). The same should apply to 'Add Selection To Next Find Match'..

Slightly related: #19483

[alexdima]

Let's track in #15774