feat(plugins): #91 natural support of venv's and requirements.

[str-anger]

This code adds a few actions, which happen by default for each plugin at first start:

1. venv in created, if doesn't exist
2. if requirements.txt is present, $venv-python -m pip install -r requirements.txt
3. If pyproject.toml is present, $venv-python -m pip install .

$python variable is used in scripts to point to a venv python.

[github-actions[bot]]

Coverage Report

File	Stmts	Miss	Cover	Missing
aqueductcore/backend
context.py	33	4	88%	48–52, 59–60
main.py	19	4	79%	21–24, 31
session.py	13	4	69%	24–28
aqueductcore/backend/models
orm.py	31	1	97%	58
plugin.py	151	14	91%	53, 56, 80–81, 88, 94, 96–97, 175, 217, 221, 246, 252, 260
aqueductcore/backend/routers
files.py	85	2	98%	157–158
frontend.py	24	11	54%	22–33, 37
aqueductcore/backend/routers/graphql
mutations_schema.py	52	2	96%	42, 116
query_schema.py	45	2	96%	66–68
router.py	11	1	91%	15
aqueductcore/backend/routers/graphql/mutations
experiment_mutations.py	21	1	95%	29
aqueductcore/backend/routers/graphql/resolvers
experiment_resolver.py	25	2	92%	28, 36
tags_resolver.py	25	3	88%	14, 44, 46
aqueductcore/backend/services
experiment.py	217	32	85%	82, 111–124, 154, 188, 194, 240, 243, 268, 299, 349, 355, 384, 390, 398, 428, 435, 443, 473–479, 486–490, 502–505
plugin_executor.py	85	9	89%	46–47, 63, 78, 81, 102, 147–153, 203
validators.py	33	2	94%	41, 46
TOTAL	1095	94	91%

Tests	Skipped	Failures	Errors	Time
88	1 :zzz:	0 :x:	0 :fire:	24.192s :stopwatch: