Inconsistent handling of eltype Decimals.Decimal (with silent errors?)

First of all, thank you for the amazing package! I have noticed unexpected behaviour that I wanted to point out.

**Expected behaviour:** rational numbers like 1.0 and 0.1 will be represented as Float; they can be saved and loaded again.

**Actual behaviour:**
When writing column with eltype Decimals.Decimal, `Arrow.write(filename,df)` will give a method error (see below) and `Arrow.write(filename,df;compress=:lz4)` will complete without an error, but the resulting table is wrong when re-read (see MWE below).

I've had a quick look at the code base and I cannot see any type checks - are those left to the user / MethodErrors?

MWE:
```
using Decimals
using DataFrames, Arrow

df=DataFrame(:a=>[Decimal(2.0)])

# this will fail with error that Decimal cannot be saved
Arrow.write("test.feather", df)
# nested task error: MethodError: no method matching write(::IOBuffer, ::Decimals.Decimal)

# this will succeed
Arrow.write("test.feather", df;compress=:lz4)

# but the loaded dataframe will be rubbish
df2=Arrow.Table("test.feather")|>DataFrame
# 1×1 DataFrame
# Row │ a
# │ Float64
# ─────┼─────────────
# 1 │ 2.1509e-314

```

Error stack trace from Arrow.write() without a keyword argument:
> ERROR: TaskFailedException
Stacktrace:
[1] wait
@ ./task.jl:345 [inlined]
[2] close(writer::Arrow.Writer{IOStream})
@ Arrow ~/.julia/packages/Arrow/ZlMFU/src/write.jl:230
[3] open(::Arrow.var"#120#121"{DataFrame}, ::Type, ::Vararg{Any}; kwargs::Base.Pairs{Symbol, Bool, Tuple{Symbol}, NamedTuple{(:file,), Tuple{Bool}}})
@ Base ./io.jl:386
[4] #write#119
@ ~/.julia/packages/Arrow/ZlMFU/src/write.jl:57 [inlined]
[5] write(file_path::String, tbl::DataFrame)
@ Arrow ~/.julia/packages/Arrow/ZlMFU/src/write.jl:56
[6] top-level scope
@ REPL[14]:1
> nested task error: MethodError: no method matching write(::IOBuffer, ::Decimals.Decimal)
Closest candidates are:
write(::IO, ::Any) at io.jl:672
write(::IO, ::Any, ::Any...) at io.jl:673
write(::Base.GenericIOBuffer, ::UInt8) at iobuffer.jl:442
...
Stacktrace:
[1] write(io::IOBuffer, x::Decimals.Decimal)
@ Base ./io.jl:672
[2] writearray(io::IOStream, #unused#::Type{Decimals.Decimal}, col::Vector{Union{Missing, Decimals.Decimal}})
@ Arrow ~/.julia/packages/Arrow/ZlMFU/src/utils.jl:50
[3] writebuffer(io::IOStream, col::Arrow.Primitive{Union{Missing, Decimals.Decimal}, Vector{Union{Missing, Decimals.Decimal}}}, alignment::Int64)
@ Arrow ~/.julia/packages/Arrow/ZlMFU/src/arraytypes/primitive.jl:102
[4] write(io::IOStream, msg::Arrow.Message, blocks::Tuple{Vector{Arrow.Block}, Vector{Arrow.Block}}, sch::Base.RefValue{Tables.Schema}, alignment::Int64)
@ Arrow ~/.julia/packages/Arrow/ZlMFU/src/write.jl:365
[5] macro expansion
@ ~/.julia/packages/Arrow/ZlMFU/src/write.jl:149 [inlined]
[6] (::Arrow.var"#122#124"{IOStream, Int64, Tuple{Vector{Arrow.Block}, Vector{Arrow.Block}}, Base.RefValue{Tables.Schema}, Arrow.OrderedChannel{Arrow.Message}})()
@ Arrow ./threadingconstructs.jl:258

**Package version**
[69666777] Arrow v2.3.0
[a93c6f00] DataFrames v1.3.4
[194296ae] LibPQ v1.14.0

**versioninfo()** (but it was the same on 1.7)
Julia Version 1.8.0
Commit 5544a0fab76 (2022-08-17 13:38 UTC)
Platform Info:
OS: macOS (arm64-apple-darwin21.3.0)
CPU: 8 × Apple M1 Pro
WORD_SIZE: 64
LIBM: libopenlibm
LLVM: libLLVM-13.0.1 (ORCJIT, apple-m1)
Threads: 6 on 6 virtual cores

Reproduce the MWE with Decimals.Decimal and compare Arrow.write behavior with and without compress=:lz4. Start in src/write.jl, src/utils.jl at writearray, and src/arraytypes/primitive.jl at writebuffer; inspect how unsupported values are handled. Done means the Decimal case behaves consistently and does not silently produce corrupted data.

Written by the indexing model from the issue text.