copilot-core: Remove deprecated fields of Copilot.Core.Expr.UExpr. Refs #636.

[ivanperez-keera]

Remove the deprecated fields of the type Copilot.Core.Expr.UExpr, as prescribed in the solution proposed for #636.

[ivanperez-keera]

Change Manager: The commit message for the main commit has a grammatical error (singular instead of plural).

[ivanperez-keera]

Implementor: Fix implemented, review requested.

[ivanperez-keera]

Change Manager: Verified that:

• Solution is implemented:
  • The code proposed compiles and passes all tests. Details:
    Build log: https://app.travis-ci.com/github/Copilot-Language/copilot/builds/275614061
  • The solution proposed produces the expected result. Details:
    The following Dockerfile tries to import the deprecated record fields, succeeding only when the import fails, after which prints the message "Success":

    FROM ubuntu:focal
    ENV DEBIAN_FRONTEND=noninteractive
    RUN apt-get update
    RUN apt-get install --yes \
    libz-dev \
    git \
    curl \
    gcc \
    g++ \
    make \
    libgmp3-dev \
    pkg-config \
    z3
    RUN mkdir -p $HOME/.ghcup/bin
    RUN curl https://downloads.haskell.org/~ghcup/0.1.40.0/x86_64-linux-ghcup-0.1.40.0 -o $HOME/.ghcup/bin/ghcup
    RUN chmod a+x $HOME/.ghcup/bin/ghcup
    ENV PATH=$PATH:/root/.ghcup/bin/
    ENV PATH=$PATH:/root/.cabal/bin/
    SHELL ["/bin/bash", "-c"]
    RUN ghcup install ghc 9.10.1
    RUN ghcup install cabal 3.2
    RUN ghcup set ghc 9.10.1
    RUN cabal update
    SHELL ["/bin/bash", "-c"]
    CMD git clone $REPO && cd $NAME && git checkout $COMMIT && cd .. \
    && cabal v1-sandbox init \
    && cabal v1-install alex happy --constraint='happy <= 2' \
    && cabal v1-install $NAME/copilot/ \
    $NAME/copilot-c99/ \
    $NAME/copilot-core/ \
    $NAME/copilot-prettyprinter/ \
    $NAME/copilot-interpreter/ \
    $NAME/copilot-language/ \
    $NAME/copilot-libraries/ \
    $NAME/copilot-theorem/ \
    && ! cabal v1-exec -- runhaskell <<< 'import Copilot.Core(uExprExpr, uExprType); main = return ()' \
    && echo "Success"

    Command (substitute variables based on new path after merge):

    $ docker run -e REPO=https://github.com/ivanperez-keera/copilot -e NAME=copilot -e COMMIT=2f4cc73a5f6db04fdd3bbabca6e52d35d011836e copilot-verify-634
    

• Implementation is documented. Details:
  No updates needed; change removes definitions not mentioned in the documentation.
• Change history is clear.
• Commit messages are clear.
• Changelogs are updated.
• Examples are updated. Details:
  No updates needed; change removes definitions not mentioned in the examples.
• Author is internal or has provided signed CLA.
• Required version bumps are evaluated. Details:
  Bump required; change affects the API.