Minor fixed

- No new features
- Applied some patches from HashBucket to SetBucket
- Removed unused code in QueueBucket, HashBucket, SetBucket
- Fixed exception message in Bucket
- Fixed HashBucket.csproj (not sure why didn't get in in last commit)
Code style: whitespace fix
Static field in generic type -> non-generic type
Renamed non-generic type Bucket to BucketHelper
Moved BucketHelper to a new file
Moved BucketHelper to a new file (updated projet)

- Now I know I missed that the last time
Code style: whitespace fix
Named status constants

Less magic numbers
IsOperationSafe returns bool (as is was intended)

IsOperationSafe now returns bool, it returned int previously for debug
purposes. Thanks to this there are now less magic numbers.
Constant fix

The code used the wrong constant (correct value, wrong name)
Added BucketStatus enum

BucketStatus replaces the named status constants
Moved BucketStatus to a separated file
IsOperationSafe new returns bool
QueueBucket now uses BucketStatus
IsOperationSafe now returns bool
Added missing constant references
Reordered IsOperationSafe
Removed unnecessary initialization
Removed unnecessary initialization
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