"fixed" filter naming

[gogonzo]

not possible to change the selected value(s) by the user. Once set, this filter will always return the same logical expression.

@lcd2yyz @donyunardi @chlebowa @kartikeyakirar @m7pr

[chlebowa]

I like both static and fixed, with a slight preference for static.

[m7pr]

the same!

[gogonzo]

Since there is a draw between fixed and static. There is no reason to change fixed to static