Strip newline on show(::Operation)

[mofeing]

Base.show on Operation prints too many newlines. This PR fixes that by printing to a IOBuffer first and stripping the newlines before printing to the original IO.

It also adds the call to mlirOpPrintingFlagsDestroy destructor.

Before

julia> MLIR.IR.create_operation("asdfs.asdfsa", MLIR.IR.Location(); results=[MLIR.IR.MLIRType(Bool)])
%0 = "asdfs.asdfsa"() : () -> i1



julia>

After

julia> MLIR.IR.create_operation("asdfs.asdfsa", MLIR.IR.Location(); results=[MLIR.IR.MLIRType(Bool)])
%0 = "asdfs.asdfsa"() : () -> i1

julia>

[codecov-commenter]

Codecov Report

Attention: 4 lines in your changes are missing coverage. Please review.

Comparison is base (d239921) 41.04% compared to head (5785ce8) 40.84%.

Files	Patch %	Lines
src/IR/IR.jl	0.00%	4 Missing ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##             main      #22      +/-   ##
==========================================
- Coverage   41.04%   40.84%   -0.20%     
==========================================
  Files           6        6              
  Lines         614      612       -2     
==========================================
- Hits          252      250       -2     
  Misses        362      362              

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[Pangoraw]

Thanks!