Bugfix: logger LWC Initialization Message

[jongpie]

Fixed #870 by updating the logger LWC initialization message to only print when JavaScript console logging is enabled via LoggerSettings__c. Also resolved some test isolation issues in logger.test.js + test improvements + code cleanup

• Updated loggerService.js to only call console.info() with an init message ('logger component initialized') when console logging is enabled via LoggerSettings__c.IsJavaScriptConsoleLoggingEnabled__c
• Replaced enableSystemMessages() and disableSystemMessages() in loggerService.js with a new static variable LoggerService.areSystemMessagesEnabled (intended for internal-use only)
• Updated logger.test.js to reset LoggerService.hasInitialized and LoggerService.areSystemMessagesEnabled static variables in beforeEach() (instead of afterAll())
• Switched to using jest.resetAllMocks() instead of jest.clearAllMocks() in logger.test.js for better test isolation
• Updated all test functions to consistently use all 3 logger creation methods (createLogger, getLogger, and getMarkupLogger)

Also include a 🤏 liiiiiiitle bit of scope creep:

• Updated all Jest tests to import createElement from '@lwc/engine-dom' (instead of 'lwc')
• Updated the project's threshold for code coverage in codecov.yml to compensate for the lower code coverage in LWC tests for now (currently around ~86%). Eventually, tests & code coverage for LWC will be improved - but for now, the constant pipeline alerts from codecov.io aren't particularly helpful 😅
• Cleaned up a small code block in LogBatchPurger using the null coalescing operator (??) to reduce the lines of code needed
• Corrected the label on field LoggerScenarioRule__mdt.IsLogAssignmentEnabled__c to use the term Logger Scenario, instead of the deprecated term Log Scenario

[jongpie]

@jamessimone random readability/style-preference question for you - for imports like this (with a default + named exports), do you go for a one-liner? Or do you like to keep them separated?

Suggested change

	import { BrowserContext } from '../loggerService';
	import LoggerService from '../loggerService';
	import LoggerService, { BrowserContext } from '../loggerService';

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.50%. Comparing base (b34b2c0) to head (3296b6b).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #884      +/-   ##
==========================================
+ Coverage   86.19%   91.50%   +5.31%     
==========================================
  Files          17       58      +41     
  Lines        1318     6312    +4994     
  Branches      199      199              
==========================================
+ Hits         1136     5776    +4640     
- Misses        162      516     +354     
  Partials       20       20              

Flag	Coverage Δ
Apex	92.91% <100.00%> (?)
LWC	86.13% <100.00%> (-0.06%)	⬇️

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