Fix 'trusted-set-constant' — determine string values more precisely

[maximtop]

If you add the following rule:

example.org#%#//scriptlet('trusted-set-constant', 'test', 'no')

you'll encounter the following error:

trusted-set-constant: TypeError: 'no' value type can't be inferred: SyntaxError: Unexpected token 'o', "no" is not valid JSON

This error forces you to wrap 'no' in additional quotes to make it valid.

[AdamWr]

Isn't it expected behavior?
According to https://github.com/AdguardTeam/Scriptlets/blob/master/wiki/about-trusted-scriptlets.md#-%EF%B8%8F-trusted-set-constant:

value — required, an arbitrary value to be set; value type is being inferred from the argument, e.g 500 will be set as number; to set string type value wrap argument into another pair of quotes: "500";

[maximtop]

but "no" does not look like a number, right?

[AdamWr]

What about true, false or null, like in examples?
I still think that it's expected, maybe it can be somehow improved and if it's a string it could be converted automatically but we should take into consideration some values which can be used as other type.

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{} and [] also should not be converted.

example.org#%#//scriptlet('trusted-set-constant', 'foo', '{}')
example.org#%#//scriptlet('trusted-set-constant', 'bar', '[]')