Update apache client 5.6 + correct gzip handling

[l-trotta]

Thank you @wilkinsona for suggesting the correct way to handle gzip responses and @ok2c for providing a fix for the client not retrieving entity metadata in the response consumer.

The apache httpclient5 version 5.6 introduces a change where it automatically decompresses gzip responses, leaving the original headers untouched. The java client used headers to detect gzip content, which would no longer work, this PR fixes it by checking the entity details instead of the headers.

The PR also updates the default client from httpclient5 5.4 to 5.6.

Closes #1134.

[github-actions]

The backport to 9.1 failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-9.1 9.1
# Navigate to the new working tree
cd .worktrees/backport-9.1
# Create a new branch
git switch --create backport-1143-to-9.1
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick --mainline 1 94ac310966946b128bc076df0289abc82dfe4e06
# Push it to GitHub
git push --set-upstream origin backport-1143-to-9.1
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-9.1

Then, create a pull request where the base branch is 9.1 and the compare/head branch is backport-1143-to-9.1.

[github-actions]

The backport to 9.0 failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-9.0 9.0
# Navigate to the new working tree
cd .worktrees/backport-9.0
# Create a new branch
git switch --create backport-1143-to-9.0
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick --mainline 1 94ac310966946b128bc076df0289abc82dfe4e06
# Push it to GitHub
git push --set-upstream origin backport-1143-to-9.0
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-9.0

Then, create a pull request where the base branch is 9.0 and the compare/head branch is backport-1143-to-9.0.