test: add unit tests for wallets (funding sources)

[motorina0]

All funding sources must behave uniformly. If, for example, the endpoint returns an HTTP 404 then all wallets api should return a Pending state. It is nok for some wallets to return a status and for others to raise an exception.

This PR creates the basis for checking the interface of all rest wallets. It currently only handles corelightingrest and lndrest, but will easily be extended.

The test data is specified in a JSON fixture. Adding new funding sources means updating the JSON.

A new dev dependency to pytest-httpserver has been added. This lib is used to simulate the LN Node rest responses.

Minor changes have been made to corelightningrest.py, lndrest.py and base.py in order to unify the interface.

This PR also closes: #2062

[codecov]

Codecov Report

Attention: Patch coverage is 92.24806% with 10 lines in your changes are missing coverage. Please review.

Project coverage is 59.46%. Comparing base (2161b25) to head (15cb0b4).

Files	Patch %	Lines
lnbits/wallets/base.py	80.95%	4 Missing ⚠️
lnbits/wallets/corelightningrest.py	92.72%	4 Missing ⚠️
lnbits/wallets/lndrest.py	96.22%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #2363      +/-   ##
==========================================
+ Coverage   58.73%   59.46%   +0.72%     
==========================================
  Files          65       65              
  Lines        9347     9404      +57     
==========================================
+ Hits         5490     5592     +102     
+ Misses       3857     3812      -45     

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[bitkarrot]

if one of you guys has a spare moment can you please check the unit test here: #2270

thanks in advance. :)

[prusnak]

Needs rebase to remove conflicts in poetry.lock and pyproject.toml

[motorina0]

CI mypy/pyright failures:

tests/wallets/test_rest_wallets.py:7: error: Cannot find implementation or library stub for module named "pytest_httpserver"  [import-not-found]
tests/wallets/test_rest_wallets.py:8: error: Cannot find implementation or library stub for module named "werkzeug.wrappers"  [import-not-found]
tests/wallets/test_rest_wallets.py:8: note: See https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports

Yeah, I've pushed the rebased branch then ran again poetry add --dev pytest_httpserver. Easier this way.