Small corrections to bessel pr

[Bumblebee00]

• in test/methods/rule_based/test_rule2.jl there is a testset called "special functions in rules" but is not meant to test the special functions form SpecialFunctions.jl, is meant to test only exp and sqrt. I called it special because they are shorthand notation for powers, and this complicates a bit the mathcing logic. So the test you added are not needded, i removed them and changed the name to a clearer one
• I dont really like the addition of rule 0_1_1 in the src/methods/rule_based/rules2/9 Miscellaneous/0.1 Integrand simplification rules.jl file, because those are rules executed for every expression and for most expressions this rule is useless. I moved it to src/methods/rule_based/rules2/8 Special functions/8.1 Bessel functions.jl with the index 8_1_0 so still before the other special functions rules (the tests still pass)
• would be cool to also add rules for functions like besselj0 becasue this is whats happening now:

julia> integrate(x * SpecialFunctions.besselj(0, 2x))
(1//2)*x*besselj(1, 2x)

julia> integrate(x * SpecialFunctions.besselj0(2x))
∫(x*besselj0(2x), x)

but i actually dont know it that's really useful

• test/methods/rule_based/test_special_functions.jl is ok for now because testing is a bit messy but the way to add tests is to insert them in a file in test/test_files add that filename to the list in test/rundifficulttests.jl

[codecov-commenter]

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Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 54.51%. Comparing base (85a221a) to head (49ca80a).
⚠️ Report is 39 commits behind head on main.

Files with missing lines	Patch %	Lines
...rules2/8 Special functions/8.1 Bessel functions.jl	0.00%	1 Missing ⚠️
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@@             Coverage Diff             @@
##             main     #111       +/-   ##
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+ Coverage   13.91%   54.51%   +40.60%     
===========================================
  Files          22       23        +1     
  Lines        4291     4309       +18     
===========================================
+ Hits          597     2349     +1752     
+ Misses       3694     1960     -1734     

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