Add LeapAPI support

[randomir]

In this PR we add LeapAPIClient base client, LeapAccount resource class, and the appropriate Leap API models (types) in order to support:

• fetching the active project in Leap
• listing all user projects
• fetching SAPI token for each of the available projects

[codecov-commenter]

Codecov Report

Merging #540 (3d4d545) into master (d1bf2ee) will increase coverage by 0.16%. The diff coverage is 96.61%.

@@            Coverage Diff             @@
##           master     #540      +/-   ##
==========================================
+ Coverage   86.69%   86.86%   +0.16%     
==========================================
  Files          24       24              
  Lines        3473     3524      +51     
==========================================
+ Hits         3011     3061      +50     
- Misses        462      463       +1     

Impacted Files	Coverage Δ
dwave/cloud/api/client.py	94.05% <93.75%> (+0.34%)	:arrow_up:
dwave/cloud/api/resources.py	95.72% <95.83%> (-0.01%)	:arrow_down:
dwave/cloud/api/__init__.py	100.00% <100.00%> (ø)
dwave/cloud/api/constants.py	100.00% <100.00%> (ø)
dwave/cloud/api/models.py	98.11% <100.00%> (+0.33%)	:arrow_up:

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[charleswhchan]

I believe Bulat might have some input for this feature. Can you add him to the PR as well?

[charleswhchan]

We shouldn't release this until zero downtime for Leap is completed (Q3 '23). Otherwise, calls to /leap will end up failing during by weekly deployment. Bad UX.

[randomir]

We shouldn't release this until zero downtime for Leap is completed (Q3 '23). Otherwise, calls to /leap will end up failing during by weekly deployment. Bad UX.

@charleswhchan, Aren't SAPI calls failing during SAPI deploys?!

[charleswhchan]

sapi-ws has zero downtime implemented and scheduler has a very short delay before restart, so all /sapi calls should be handled and processed as usual.

where as calls to /leap will show the maintenance page and probably return a 5xx error

[randomir]

We already use Leap API from the IDE, so I think it's fine to release this before the end of Q3. It's not like it will be visible and used by default. Currently it's not even documented; intended practically for internal use.

[arcondello]

We shouldn't release this until zero downtime for Leap is completed (Q3 '23). Otherwise, calls to /leap will end up failing during by weekly deployment. Bad UX.

My 2c is that a user who is using this feature (especially given its current semi-private nature) would understand that when Leap is down they would get an error message. So IMO while it's not an ideal user experience, the relative benefits are well worth it.

[charleswhchan]

My 2c is that a user who is using this feature (especially given its current semi-private nature) would understand that when Leap is down they would get an error message. So IMO while it's not an ideal user experience, the relative benefits are well worth it.

Rad, Bulat and myself will be meeting on Monday -- we can reach a decision then.