Improve installation supports with external builds

[mlxd]

Context: The CMake build system, and associated targets, do not fully conform to a CMake installation step. As such, to allow better reproducibility across builds, and integration with platforms such as spack, we need to make some adjustments to best support this.

Description of the Change: Change benchmark and test target names, macro variable usage and header visibility. Running cmake --install ./build following a compilation step will now install the headers and compiled binaries into a predefined target location with bin include and lib directories.

Benefits: Enables better support for installation of lightning targets, headers, and spack integration.

Possible Drawbacks:

Related GitHub Issues:

[github-actions]

Hello. You may have forgotten to update the changelog!
Please edit .github/CHANGELOG.md with:

• A one-to-two sentence description of the change. You may include a small working example for new features.
• A link back to this PR.
• Your name (or GitHub username) in the contributors section.

[codecov]

Codecov Report

Merging #403 (d86e7d8) into master (7a36b4c) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #403   +/-   ##
=======================================
  Coverage   99.88%   99.88%           
=======================================
  Files          49       49           
  Lines        4463     4463           
=======================================
  Hits         4458     4458           
  Misses          5        5           

Impacted Files	Coverage Δ
pennylane_lightning/_serialize.py	100.00% <ø> (ø)
pennylane_lightning/src/util/LinearAlgebra.hpp	100.00% <ø> (ø)
pennylane_lightning/_version.py	100.00% <100.00%> (ø)

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[chaeyeunpark]

First iteration. Looks good so far.

[multiphaseCFD]

Thanks @mlxd for the nice work and looks nice for me.

[AmintorDusko]

Nice work so far!

[vincentmr]

Hi @mlxd, looks good to me. I'm wondering, why did the benchmarks and tests got renamed with the pennylane_lightning_ prefix?

[mlxd]

Hi @mlxd, looks good to me. I'm wondering, why did the benchmarks and tests got renamed with the pennylane_lightning_ prefix?

Thanks @vincentmr. With this update, we have the option to install the built binaries into a given prefix path from CMake, and for our updates to support spack. If we installed our test runner (previously named runner) into a /usr/local/bin directory, it would be very ambiguous what it is doing (the same with the benchmarking binary). The naming update was to avoid conflicting with any other packages that have similarly named binaries, by prepending our package name to the binary names.

[AmintorDusko]

Thank you for that!

[AmintorDusko]

Hey @mlxd, black just released its new version. Before merging, please update black locally and run:
black -l 100 ./pennylane_lightning/ ./tests

[mlxd]

black -l 100 ./pennylane_lightning/ ./tests

Done. Will merge after the CI passes

[mlxd]

black -l 100 ./pennylane_lightning/ ./tests

Done. Will merge after the CI passes

[mlxd]

black -l 100 ./pennylane_lightning/ ./tests

Done. Will merge after the CI passes