Replace SF CLI with XCC CLI

[Mandrenkov]

Context: Moving forward, the CLI offered by Strawberry Fields (SF) will be replaced by the Xanadu Cloud Client (XCC) CLI.

Description of the Change:

• Removed the CLI package, tests, entry point, and Sphinx documentation.
• Updated the Hardware and cloud tutorial to use the XCC CLI.
• Added a Migration guides page to the Sphinx documentation with a CLI section under Version 0.20.0.

Benefits:

• There is no need to maintain a separate CLI for Strawberry Fields.
• Users only need to set up their Xanadu Cloud credentials once (and use them in several different projects).

Possible Drawbacks:

• There may be some initial confusion when users discover the sf entry point is missing.

Related GitHub Issues: None.

[codecov[bot]]

Codecov Report

Merging #642 (2305d64) into integrate-xanadu-cloud-client (d4c11b9) will increase coverage by 0.06%. The diff coverage is n/a.

@@                        Coverage Diff                        @@
##           integrate-xanadu-cloud-client     #642      +/-   ##
=================================================================
+ Coverage                          98.27%   98.34%   +0.06%     
=================================================================
  Files                                 77       76       -1     
  Lines                               9178     9104      -74     
=================================================================
- Hits                                9020     8953      -67     
+ Misses                               158      151       -7     

Impacted Files	Coverage Δ
strawberryfields/__init__.py	95.55% <ø> (-0.10%)	:arrow_down:

---

Continue to review full report at Codecov.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update d4c11b9...2305d64. Read the comment docs.

[Mandrenkov]

Let me know what you think of the new release notes, @josh146 or @thisac. The rest may follow a similar format.