print TOML data in alphabetical order (with "julia" at the end)

[lmiq]

With this PR, when tagging a new version of the package, the entries of [compat], [deps], [extras], etc, are printed in alphabetical order, except for julia which is is printed at the end of the list (following the Aqua style).

Currently the entries are printed in random order, as the dict is unordered when read.

This tries to address julia-vscode/julia-vscode#3634

By at least following a style in the list (it does not preserve the list, which would require TOML.parsefile to read the data into an ordered dict, option which is currently unavailable).

Example of the output (I don't know how to actually test this in the package):

julia> prj = TOML.parsefile("./Project.toml");

julia> TOML.print(prj) # current behavior
name = "PkgDev"
uuid = "149e707d-584d-56d3-88ec-740c18e106ff"
version = "1.7.3-DEV"

[deps]
Pkg = "44cfe95a-1eb2-52ea-b672-e2afdf69b78f"
URIs = "5c2747f8-b7ea-4ff2-ba2e-563bfd36b1d4"
PkgButlerEngine = "5c9c0fc8-7103-448b-bb0a-c427020e3b0b"
UUIDs = "cf7118a7-6976-5b1a-9a39-7adc72f591a4"
GitHub = "bc5e4493-9b4d-5f90-b8aa-2b2bcaad7a26"
DocumentFormat = "ffa9a821-9c82-50df-894e-fbcef3ed31cd"
RegistryTools = "d1eb7eb1-105f-429d-abf5-b0f65cb9e2c4"
JSON = "682c06a0-de6a-54ab-a142-c8b1cf79cde6"
LibGit2 = "76f85450-5226-5b5a-8eaa-529ad045b433"
Base64 = "2a0f44e3-6c83-55bd-87e4-b1978d98bd5f"
FilePathsBase = "48062228-2e41-5def-b9a4-89aafe57970f"
TOML = "fa267f1f-6049-4f14-aa54-33bafae1ed76"

[extras]
Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"

[compat]
GitHub = "5.1.1"
JSON = "0.21"
julia = "1.6"
FilePathsBase = "0.6, 0.7, 0.8, 0.9"
DocumentFormat = "4"
URIs = "1"
PkgButlerEngine = "1.2"
RegistryTools = "1"

[targets]
test = ["Test"]

julia> TOML.print(prj; sorted=true, by=key -> ifelse(key == "julia" , "1", "0$key")) # proposed in this PR
name = "PkgDev"
uuid = "149e707d-584d-56d3-88ec-740c18e106ff"
version = "1.7.3-DEV"

[compat]
DocumentFormat = "4"
FilePathsBase = "0.6, 0.7, 0.8, 0.9"
GitHub = "5.1.1"
JSON = "0.21"
PkgButlerEngine = "1.2"
RegistryTools = "1"
URIs = "1"
julia = "1.6"

[deps]
Base64 = "2a0f44e3-6c83-55bd-87e4-b1978d98bd5f"
DocumentFormat = "ffa9a821-9c82-50df-894e-fbcef3ed31cd"
FilePathsBase = "48062228-2e41-5def-b9a4-89aafe57970f"
GitHub = "bc5e4493-9b4d-5f90-b8aa-2b2bcaad7a26"
JSON = "682c06a0-de6a-54ab-a142-c8b1cf79cde6"
LibGit2 = "76f85450-5226-5b5a-8eaa-529ad045b433"
Pkg = "44cfe95a-1eb2-52ea-b672-e2afdf69b78f"
PkgButlerEngine = "5c9c0fc8-7103-448b-bb0a-c427020e3b0b"
RegistryTools = "d1eb7eb1-105f-429d-abf5-b0f65cb9e2c4"
TOML = "fa267f1f-6049-4f14-aa54-33bafae1ed76"
URIs = "5c2747f8-b7ea-4ff2-ba2e-563bfd36b1d4"
UUIDs = "cf7118a7-6976-5b1a-9a39-7adc72f591a4"

[extras]
Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"

[targets]
test = ["Test"]

julia>

[lmiq]

ps: There might be a more elegant way to put julia at the end rather than the by=key -> ifelse(key == "julia" , "1", "0$key") function.