Fixes #33073

Do not offer to remove redundant assignment if it is not parented by an explicit block with curly braces

Fixes #32856

For example, consider a redundant assignment to 'x' in `if (...) x = 1;`
Replacing 'x = 1' with an empty statement ';' is not useful, and user is most likely
going to remove the entire if statement in this case. However, we don't
want to suggest removing the entire if statement as that might lead to change of semantics.
So, we conservatively bail out from removable assignment analysis for such cases.

Fixes #32942

Prior implementation looked for specific unhandled operation tree shapes and was agressive, leading to false positives. New implementation handles only specific operation tree shapes and is much more conservative.

Fixes #32946
Fixes #32924

Fixes #32973

Unused value assignments will not be flagged in such operation blocks. Unused parameter reporting falls back to checking presence of any read references to parameters, regardless of flow feasibility of that code path.

Fixes #32959

Fixes #32923

Another case where we need PointsTo analysis for precise flow analysis, we bail out as we currently do not perform any PointsTo analysis.

Fixes #32903

We need points to analysis for properly analyzing unused assignments to ref locals, which is currently not supported.
Fixes #32855

Workaround for #31820. Issue #31821 tracks reverting this workaround once #31820 is addressed.

Bail out from unused value assignment analysis in presence of delegates passed as arguments to method invocation.

Do not report unused value assignment for VB static local assignment and unused parameter for VB Handles method parameters.

Fixes #31744

1. Do not offer remove unused local assignment for locals with error type
2. Make sure that this code fix is ordered after Add usings code fix, in case there are more similar unknown cases, by adding the ExtensionOrder attribute

Fixes #31583

Treat conversions whose operands have no side effects to be operations with no side effects, that can be removed.

Conservatively handle delegates passed as arguments to method invocations by reseting state so all the current writes are assumed to be read.
Also ensure that we report unused parameters when we bail out from flow analysis, as the latter should only prevent us from reporting unused values.