Stylecopanalyzers: Provide configuration options for SA1101/SX1101

[julianbartel]

Our coding rules generally prefer not using this, but with an exception for (static) fields, so neither SA1101 nor SX1101 match our rules.

Proposal is to provide a configuration option for this case.
I am unsure about the best way how to configure. To satisfy our use case, a simple configuration entry would be enough, like: "doNotPrefixLocalCallsExceptFields": true.
A more sophisticated configuration would be an exclusion list, like "doNotPrefixLocalCallsExcept": [ "fields" ] for SX1101 and
"prefixLocalCallsExcept": [ "methods" ] for SA1101, which is more flexible (but a bit prone regarding conflicting settings).

[sharwell]

I would certainly prefer SA1101 and SX1101 be merged into a single rule, similar to how Use Tabs Consistently was handled. However, the finer-grained control for the rule seems more relevant for the upcoming Roslyn code style feature.