Option to create sample points outside gen

[shuds13]

Address #1696

This approach does not require generator to tell you if it samples. By adding initial_sample_method="uniform"
if will create, evaluate via workers, and ingest initial_batch_size points.

May need check that using vocs.

[codecov]

Codecov Report

❌ Patch coverage is 37.50000% with 15 lines in your changes missing coverage. Please review.
✅ Project coverage is 78.19%. Comparing base (9363f9b) to head (7888bab).
⚠️ Report is 11 commits behind head on develop.

Files with missing lines	Patch %	Lines
libensemble/utils/runners.py	25.00%	14 Missing and 1 partial ⚠️

❗ There is a different number of reports uploaded between BASE (9363f9b) and HEAD (7888bab). Click for more details.

HEAD has 24 uploads less than BASE

Flag	BASE (9363f9b)	HEAD (7888bab)
	34	10

Additional details and impacted files

@@             Coverage Diff              @@
##           develop    #1697       +/-   ##
============================================
- Coverage    93.29%   78.19%   -15.11%     
============================================
  Files           81       81               
  Lines         8188     8213       +25     
  Branches      1257     1261        +4     
============================================
- Hits          7639     6422     -1217     
- Misses         358     1558     +1200     
- Partials       191      233       +42     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.