Add option param for standalone mode

[kination]

Related Issue

#43

Rationale for this change

Currently StandaloneClient instance can be created by saving data to a specific file, or to temporary file. But it executor only runs by generating temporary file, so add parameter to give specific file path.

What changes are included in this PR?

It creates client with StandaloneClient::try_new(path) if path has been defined, or StandaloneClient::try_new_temporary() if not defined.

[codecov-commenter]

Codecov Report

Merging #42 (842c775) into master (32951c3) will decrease coverage by 0.00%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master      #42      +/-   ##
==========================================
- Coverage   76.24%   76.24%   -0.01%     
==========================================
  Files         134      134              
  Lines       23023    23053      +30     
==========================================
+ Hits        17554    17576      +22     
- Misses       5469     5477       +8     

Impacted Files	Coverage Δ
ballista/rust/executor/src/main.rs	0.00% <0.00%> (ø)
datafusion/src/physical_plan/group_scalar.rs	55.29% <0.00%> (-2.03%)	⬇️
datafusion/src/physical_plan/hash_join.rs	86.42% <0.00%> (-0.18%)	⬇️
datafusion/src/physical_plan/hash_aggregate.rs	85.90% <0.00%> (-0.17%)	⬇️
datafusion/src/scalar.rs	54.03% <0.00%> (ø)
datafusion/src/execution/context.rs	92.94% <0.00%> (+0.09%)	⬆️

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[andygrove]

Hi @djKooks thanks for the PR. Because you were a contributor to the Ballista code that was donated, I believe that we need you to file a contributor license agreement with the ASF before accepting further contributions. I tried reaching you during the donation process but wasn't able to.

Instructions are here. Let me know if you need any help.

https://www.apache.org/licenses/contributor-agreements.html

Thanks!

[kination]

@andygrove thanks for review.
I've just found that my request has been refused because of some missing information. I just updated and resend it.

Please review after it has been approved 🙏