Change Schema::$typeMap to constant Schema::TYPE_MAP

[Tigrov]

The change reduces size of cache.

Q	A
Is bugfix?	❌
New feature?	❌
Breaks BC?	❌
Fixed issues	-

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (2e83366) 99.04% compared to head (4ceadd6) 99.04%.
Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##             master     #312   +/-   ##
=========================================
  Coverage     99.04%   99.04%           
  Complexity      174      174           
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  Files            13       13           
  Lines           524      524           
=========================================
  Hits            519      519           
  Misses            5        5           

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[what-the-diff]

PR Summary

• Transformation of 'typeMap' property into a constant
  The code now utilizes a permanent and unchangeable value, referred to as TYPE_MAP, replacing the formerly used variable typeMap. This ensures more stability and predictability in the code.

• Updated references to use the new 'TYPE_MAP' constant
  All previous reference points in the code where typeMap was used have now been revised to utilize the new constant TYPE_MAP.

• Added documentation for the 'TYPE_MAP' constant
  A new commentary section known as a 'docblock' has been written for TYPE_MAP to provide further information and context for this constant.

• 'TYPE_MAP' constant employed in column type assignments
  The code employed for assigning types to columns within our databases now refers to the TYPE_MAP constant. This ensures a more standardized and coherent approach to defining column types.