Implement algebra with UniformScaling

[blegat]

Closes #1989
Also fixes JuliaLang/julia#32374 for JuMP variables

[codecov]

Codecov Report

Merging #1993 into master will decrease coverage by 0.01%.
The diff coverage is 86.95%.

@@            Coverage Diff             @@
##           master    #1993      +/-   ##
==========================================
- Coverage   88.86%   88.84%   -0.02%     
==========================================
  Files          33       33              
  Lines        4282     4295      +13     
==========================================
+ Hits         3805     3816      +11     
- Misses        477      479       +2

Impacted Files	Coverage Δ
src/parse_expr.jl	85.38% <78.57%> (ø)	⬆️
src/operators.jl	83.26% <90.62%> (-0.07%)	⬇️
src/macros.jl	91.39% <0%> (+0.01%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 36dc086...9a2e00e. Read the comment docs.

[codecov]

Codecov Report

Merging #1993 into master will decrease coverage by 0.01%.
The diff coverage is 90%.

@@            Coverage Diff            @@
##           master   #1993      +/-   ##
=========================================
- Coverage   89.11%   89.1%   -0.02%     
=========================================
  Files          33      33              
  Lines        4299    4312      +13     
=========================================
+ Hits         3831    3842      +11     
- Misses        468     470       +2

Impacted Files	Coverage Δ
src/parse_expr.jl	85.38% <78.57%> (ø)	⬆️
src/operators.jl	86.24% <96.15%> (-0.12%)	⬇️
src/macros.jl	91.39% <0%> (+0.01%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 4fdad2b...425f007. Read the comment docs.