Move previously snovault-based project support to dcicutils.project_utils (C4-1032, C4-1033, C4-1034)

[netsettler]

Changes in service of C4-1032 and C4-1033 and C4-1034:

• New module project_utils with support for Project mechanism.

  • New decorators ProjectRegistry and C4ProjectRegistry

  • New class Project and C4Project

• In qa_utils:

  • In class MockFileSystem:

  • New method abspath

  • New method chdir

  • New method expanduser

  • New method getcwd

  • New method mock_exists_open_remove_abspath_getcwd_chdir (context manager)

• In lang_utils (for C4-1034):

  • Teach EnglishUtils.string_pluralize about words ending in -ses because cgap-portal needs this.

[coveralls]

Pull Request Test Coverage Report for Build 5082557898

• 303 of 304 (99.67%) changed or added relevant lines in 3 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.8%) to 75.64%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
dcicutils/project_utils.py	265	266	99.62%
<!--	Total:	303	304	99.67%	-->

Totals
Change from base Build 5080784541:	0.8%
Covered Lines:	7390
Relevant Lines:	9770

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💛 - Coveralls