Migrate from std::allocator type to pmr

[kammce]

• Add StaticMonotonicAllocator() class which statically allocates a buffer, and a monotonic_buffer_resource, and records the memory allocated.
• Remove FixedAllocator and all of the supporting shorthand classes and files as they are no longer needed.
• Update allocator_test.cpp to reflect the new allocator
• Update libraries that depend on FixedAllocator to use the new pmr Allocator.

Resolves #1406

[codecov[bot]]

Codecov Report

Merging #1407 (fd7542e) into master (f0cadcd) will decrease coverage by 0.4%. The diff coverage is 37.5%.

@@           Coverage Diff            @@
##           master   #1407     +/-   ##
========================================
- Coverage    46.7%   46.4%   -0.3%     
========================================
  Files         184     180      -4     
  Lines       10219   10151     -68     
  Branches     4356    4358      +2     
========================================
- Hits         4770    4705     -65     
+ Misses       1685    1678      -7     
- Partials     3764    3768      +4     

Flag	Coverage Δ
unittests	46.4% <37.5%> (-0.3%)	:arrow_down:

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
library/L3_Application/commands/i2c_command.hpp	0.0% <0.0%> (ø)
library/utility/test/allocator_test.cpp	20.0% <20.0%> (-44.5%)	:arrow_down:
library/L3_Application/commandline.hpp	35.3% <50.0%> (ø)
library/utility/allocator.hpp	87.5% <87.5%> (+10.6%)	:arrow_up:

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