GH-37891: [C++] Pass shared_ptr<DataType> by value in SliceBuffer-related constructors

[chrisxu333]

Rationale for this change

These changes facilitate the process of moving newly constructed shared_ptr without the need of adding a refcount and still support cases where a reference of a shared_ptr is passed from caller.

What changes are included in this PR?

• Change SliceBuffer-related constructor to take shared_ptr by value instead of const &.
• Change SliceBufferSafe-related constructor to take shared_ptr by value instead of const &.
• Change SliceMutableBufferSafe -related constructors to take shared_ptr by value instead of const &.

Are these changes tested?

Yes.

Are there any user-facing changes?

• The SliceBuffer() function now take the shared_ptr parameter value instead of const &.

• GitHub Issue: [C++] Pass shared_ptr<DataType> by value to parametric type constructors #37891

[pitrou]

@chrisxu333 The changes look good to me, but can you ensure the PR title accurately describes its contents? Thank you!

[chrisxu333]

@chrisxu333 The changes look good to me, but can you ensure the PR title accurately describes its contents? Thank you!

Sure will do. Also there're more changes to make besides this, I made this one first just to confirm my understanding aligns with the need :)

[pitrou]

@chrisxu333 It seems the CI actions were skipped because your PR very recently had "wip" in its title :) If you push another commit it will hopefully allow triggering a full CI run.

[chrisxu333]

@chrisxu333 It seems the CI actions were skipped because your PR very recently had "wip" in its title :) If you push another commit it will hopefully allow triggering a full CI run.

Sure, I changed it already. Could you please help review this? :)