Move datafusion-cli to new crate

[Dandandan]

Which issue does this PR close?

Closes #218

Rationale for this change

• Building DataFusion fetches extra dependencies (clap rustyline and transitive dependencies) unneeded for the rest of DataFusion, slowing the development cycle down a bit (mainly for clean builds).
• Installing the binary using cargo is currently a bit more cumbersome, cargo install datafusion --bin datafusion-cli --release
• dependency constraints on the cli dependencies potentially can cause conflicts for DataFusion consumers

Version	Nr dependencies
Master	199
PR	186

What changes are included in this PR?

• Moves the source code & dependencies to datafusion-cli
• Drive-by change to make the default batch size a more reasonable value (8192 instead of >1M)
• Documentation updates
• Update rustyline version

Are there any user-facing changes?

Users should be able to use datafusion-cli now instead of using the bin option inside of datafusion.

[codecov-commenter]

Codecov Report

Merging #231 (220fcf0) into master (23d02bb) will increase coverage by 0.00%.
The diff coverage is 0.00%.

@@           Coverage Diff           @@
##           master     #231   +/-   ##
=======================================
  Coverage   76.46%   76.46%           
=======================================
  Files         135      134    -1     
  Lines       23250    23249    -1     
=======================================
  Hits        17777    17777           
+ Misses       5473     5472    -1     

Impacted Files	Coverage Δ
datafusion-cli/src/main.rs	0.00% <0.00%> (ø)

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[andygrove]

The Dockerfile will also need to be updated (it looks like it has incorrect paths). The Dockerfile also probably needs moving to the new datafusion-cli folder too.

[Dandandan]

The Dockerfile will also need to be updated (it looks like it has incorrect paths). The Dockerfile also probably needs moving to the new datafusion-cli folder too.

Thanks, I updated the Dockerfile

[andygrove]

LGTM. I can't approve this PR for some reason. Maybe a GitHub glitch .. I will check again later.

[alamb]

LGTM too. Thanks @Dandandan