NET-1651 S1854: Improve message when issue is raised in the context of increment or decrement operator

[mary-georgiou-sonarsource]

The current message that this rule is raising is causing confusion in the context of increment and decrement operators.
See community posts here and here.

The message should be improved to give a more accurate proposal as action, for example, instead of just remove this assignment it can be replace this not used assignment with [variable]+1 and even explain a bit more that these operators are creating an assignment in the background.

[pavel-mikula-sonarsource]

Moved to NET-1651