Add more views, dots and specialised model functions

[sschlenkrich]

This PR adds updates scenario valuation methods to avoid some allocations.

• add ScalarValue payoff
• add (log_)compounding_factor methods
• add (log_)zero_bonds methods

[codecov-commenter]

Codecov Report

Attention: 9 lines in your changes are missing coverage. Please review.

Comparison is base (628bfe6) 98.74% compared to head (257cc49) 98.17%.

Files	Patch %	Lines
src/models/Model.jl	63.63%	4 Missing ⚠️
src/paths/PathMethods.jl	92.45%	4 Missing ⚠️
src/models/rates/SwapRateVolatility.jl	92.30%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #59      +/-   ##
==========================================
- Coverage   98.74%   98.17%   -0.58%     
==========================================
  Files          61       61              
  Lines        3195     3287      +92     
==========================================
+ Hits         3155     3227      +72     
- Misses         40       60      +20     

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