Optimize qualified identifier creation

[SupunS]

Description

A micro-optimization:

• Simply return the identifier, if there are no containers.
• Avoid appending by creating the identifier-array at the lowest level of the chain (when the size is known).
• Calculate the buffer size on the fly, and grow the string-builder buffer at once.

name                                                  old time/op    new time/op    delta
QualifiedIdentifierCreation/One_level-12              24.6ns ± 4%     2.0ns ± 1%   -91.96%  (p=0.008 n=5+5)
QualifiedIdentifierCreation/Three_levels-12            197ns ± 4%     105ns ± 7%   -46.93%  (p=0.008 n=5+5)

name                                                  old alloc/op   new alloc/op   delta
QualifiedIdentifierCreation/One_level-12               8.00B ± 0%     0.00B       -100.00%  (p=0.008 n=5+5)
QualifiedIdentifierCreation/Three_levels-12             120B ± 0%       64B ± 0%   -46.67%  (p=0.008 n=5+5)

name                                                  old allocs/op  new allocs/op  delta
QualifiedIdentifierCreation/One_level-12                1.00 ± 0%      0.00       -100.00%  (p=0.008 n=5+5)
QualifiedIdentifierCreation/Three_levels-12             4.00 ± 0%      2.00 ± 0%   -50.00%  (p=0.008 n=5+5)

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• Targeted PR against master branch
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work
• Code follows the standards mentioned here
• Updated relevant documentation
• Re-reviewed Files changed in the Github PR explorer
• Added appropriate labels

[turbolent]

This is a great optimization! This code is called often, so optimizing it makes a lot of sense 👍

[codecov-commenter]

Codecov Report

Merging #948 (1222de9) into master (a0332c6) will increase coverage by 0.03%.
The diff coverage is 92.00%.

@@            Coverage Diff             @@
##           master     #948      +/-   ##
==========================================
+ Coverage   74.05%   74.08%   +0.03%     
==========================================
  Files         269      269              
  Lines       33074    33089      +15     
==========================================
+ Hits        24492    24515      +23     
+ Misses       7453     7445       -8     
  Partials     1129     1129              

Flag	Coverage Δ
unittests	74.08% <92.00%> (+0.03%)	⬆️

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

Impacted Files	Coverage Δ
runtime/sema/type.go	87.68% <92.00%> (+0.40%)	⬆️
runtime/interpreter/interpreter.go	90.05% <0.00%> (-0.09%)	⬇️
runtime/runtime_storage.go	87.87% <0.00%> (+1.01%)	⬆️

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[turbolent]

Nice work!