Centred "Contents" in TOC in twocolumn document with custom sections

I want to adjust the TOC for my twocolumn document. I want to have the word “Contents” at the top and centre of the page, and the toc entries following in two columns afterwards.

I found this which shows me how to do this; but

1) it conflicts with my use of the titletoc and titlesec packages. This is because the TOC seems itself to be a section.

2) it is overly specific in formatting of the toc entries.
I would like to format the entries themselves with titletoc as follows

titlecontents{section} [0pt] { } {thecontentslabel.enspace} { } {leadershbox to 1em{hss.hss}hfill thecontentspage} []

How can I get my formatting of the sections and toc entries, as well as centering the word “Contents” in the TOC of my doc?

The result so far is this

The MWE is:

documentclass[12pt,oneside,twocolumn]{article}
usepackage[a4paper, bottom=2cm, columnsep=2.0cm,top=2cm, left=1in, right=1cm ] {geometry}
usepackage{titlesec}
usepackage[]{titletoc}
titlespacing{section}{0pt}{4ex}{-0.5parskip}
titleformat{section}[hang]{raggedrightnormalfontlargebfseries}{thesection.}{1ex}{}[]

makeatletter
renewcommand*{tableofcontents}{%
  if@twocolumn
    @restonecolfalse
  else
    @restonecoltrue
  fi
  twocolumn[section*{centeringcontentsname}]%
  @mkboth{MakeUppercasecontentsname}%
          {MakeUppercasecontentsname}%
  thispagestyle{plain}%
  @starttoc{toc}%
  if@restonecol
    onecolumn
  else
    clearpage
  fi
}
makeatother
begin{document}
tableofcontents
newpage

section{Section 1}
section{Section 2}
section{Section 3}
section{Section 4}
section{Section 5}
section{Section 6}
section{Section 7}
section{Section 8}
section{Section 9}
section{Section 10}
section{Section 11}
section{Section 12}
section{Section 13}
section{Section 14}
section{Section 15}
section{Section 16}
section{Section 17}
section{Section 18}
section{Section 19}
section{Section 20}
section{Section 21}
section{Section 22}
section{Section 23}
section{Section 24}
section{Section 25}
section{Section 26}
section{Section 27}
section{Section 28}
section{Section 29}

end{document}

documentclass{article}
usepackage{multicol}

usepackage{titlesec}
titlespacing{section}{0pt}{4ex}{-0.5parskip}
titleformat{section}[hang]{raggedrightnormalfontlargebfseries}{thesection.}{1ex}{}[]

usepackage[]{titletoc}
titlecontents{section} [0pt] { } {thecontentslabel.enspace} { } {leadershbox to 1em{hss.hss}hfill  thecontentspage} []

makeatletter
renewcommandtableofcontents{%
@starttoc{toc}%
}
makeatother
makeatletter
renewcommandtableofcontents{%
    @starttoc{toc}%
}
makeatother

begin{document}

begin{center}
Large
textbf{Contents}  
end{center}

begin{multicols}{2}

tableofcontents
newpage

section{Section 1}
section{Section 2}
section{Section 3}
section{Section 4}
section{Section 5}
section{Section 6}
section{Section 7}
section{Section 8}
section{Section 9}
section{Section 10}
section{Section 11}
section{Section 12}
section{Section 13}
section{Section 14}
section{Section 15}
section{Section 16}
section{Section 17}
section{Section 18}
section{Section 19}
section{Section 20}
section{Section 21}
section{Section 22}
section{Section 23}
section{Section 24}
section{Section 25}
section{Section 26}
section{Section 27}
section{Section 28}
section{Section 29}
end{multicols}


end{document}