Changing AggregationRequest to Generate Based on Provided Argument Order

[shacharPash]

Before this PR, the FT.AGGREGATE arguments would always appear in this order, 0 or 1 times, regardless of the order in which the user defined them:

public void SerializeRedisArgs()
{
    Verbatim();
    Load();
    Timeout();
    Apply();
    GroupBy();
    SortBy();
    Limit();
    Filter();
    Cursor();
    Params();
    Dialect();
}

According to the aggregation Core concepts :

The basic idea of an aggregate query is this:

• Perform a search query, filtering for records you wish to process.
• Build a pipeline of operations that transform the results by zero or more sequences of:
  • Group and reduce: grouping by fields in the results, and applying reducer functions to each group.
  • Sort: sort the results based on one or more fields.
  • Apply transformations: apply mathematical and string functions on fields in the pipeline, optionally creating new fields or replacing existing ones.
  • Limit: limit the result, regardless of how the result is sorted.
  • Filter: filter the results (post-query) based on predicates relating to its values.

The pipeline is dynamic and re-entrant, and every operation can be repeated. For example, you can group by property X, sort the top 100 results by group size, then group by property Y and sort the results by some other property, then apply a transformation on the output.

So, after this PR the user can write more than one of each argument and the order is the order the user call the arguments.

Closes #230

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 98.21429% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 94.17%. Comparing base (2ec5430) to head (7c134e5).
Report is 1 commits behind head on master.

Files	Patch %	Lines
src/NRedisStack/Search/AggregationRequest.cs	97.67%	0 Missing and 1 partial ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##           master     #259      +/-   ##
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- Coverage   94.27%   94.17%   -0.11%     
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  Files          87       87              
  Lines        5367     5270      -97     
  Branches      503      489      -14     
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- Hits         5060     4963      -97     
  Misses        181      181              
  Partials      126      126              

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[gerzse]

LGTM, just some cosmetic comments.

[gerzse]

These docstring changes should be reverted, I guess.

[gerzse]

Sounds like no harm to make it params. But then the same can be done for other methods?

[shacharPash]

I wasn't sure because this signature allows to send only MAX without any field, although at least one field must be sent, thats why I added the if(fields.Length > 0),
but right now I looked again and this is the syntax of sortby:
[ SORTBY nargs [ property ASC | DESC [ property ASC | DESC ...]] [MAX num]
so sending only MAX without any field should be possible.