names() and get() for a specific section should always return parameters in the same order

[bgctw]

I encountered the following behaviour in a complex Chains object inspected from Infiltrator prompt,
where names and get return variables in a different order (similar to #326):

infil> names(df.chn, :u0)                                                                                                                                                                    
11-element Vector{Symbol}:                                                                                                                                                                   
 :s₊α_R0                                                                                                                                                                                     
 :s₊R_N0                                                                                                                                                                                     
 :s₊I_P0                                                                                                                                                                                     
 :s₊R_P0                                                                                                                                                                                     
 :s₊L_P0                                                                                                                                                                                     
 :s₊α_P0                                                                                                                                                                                     
 :s₊L0                                                                                                                                                                                       
 :s₊L_N0                                                                                                                                                                                     
 :s₊I_N0                                                                                                                                                                                     
 :s₊R0                                                                                                                                                                                       
 :s₊B0                                                                                                                                                                                       
                                                                                                                                                                                                                                                                                                                                                                                       
infil> keys(get(df.chn, section=:u0))                                                                                                                                                                                                                                                                                                                                                   
(:s₊R_N0, :s₊R_P0, :s₊L_N0, :s₊I_N0, :s₊L0, :s₊α_R0, :s₊B0, :s₊L_P0, :s₊α_P0, :s₊R0, :s₊I_P0)   

I failed to construct a MWE. The following works as expected:

ulia> chn1 = Chains(rand(100, 4, 2), [:a, :b, :c, :d]);

julia> chn1s = set_section(chn1, Dict(:parameters => [:a,:b], :u0 => [:d, :c]));

julia> names(chn1s, :u0)
2-element Vector{Symbol}:
 :d
 :c

julia> keys(get(chn1s, section = :u0))
(:d, :c)

Encountered on Julia 1.9.2 and MCMCChains v6.0.4

[penelopeysm]

Closed by #466