Performance improvements

[lkdvos]

Here I address an issue/regression since TensorKit v0.16.
Due to a change in upstream, we used to allocate tensors with similar, and now are using tensoralloc more consistently.
However, tensoralloc was effectively making sparse blocktensormaps dense, which is resolved in this PR.
Additionally, I took the time to more properly handle bounds checking, further reducing some of the overhead.
Finally, where the boundschecks are still happening, I avoided some allocations by specializing size to avoid some calls to dual, which allocates on spaces.

[codecov]

Codecov Report

❌ Patch coverage is 62.96296% with 10 lines in your changes missing coverage. Please review.
✅ Project coverage is 54.51%. Comparing base (7d3fd12) to head (2c2119e).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/tensors/indexmanipulations.jl	16.66%	5 Missing ⚠️
src/auxiliary/sparsetensorarray.jl	71.42%	4 Missing ⚠️
src/tensors/abstractblocktensor/abstractarray.jl	83.33%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #43      +/-   ##
==========================================
+ Coverage   54.36%   54.51%   +0.15%     
==========================================
  Files          17       17              
  Lines        1398     1394       -4     
==========================================
  Hits          760      760              
+ Misses        638      634       -4     

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