Replace all references to the develop branch

[npepinpe]

Description

Replaces all the references to the develop branch in build scripts, licenses, and documentation, and refer to the new main branch. This should be merged immediately after the develop branch is renamed to avoid issues in other PRs.

Definition of Done

Not all items need to be done depending on the issue and the pull request.

Code changes:

• The changes are backwards compatibility with previous versions
• If it fixes a bug then PRs are created to backport the fix to the last two minor versions. You can trigger a backport by assigning labels (e.g. backport stable/0.25) to the PR, in case that fails you need to create backports manually.

Testing:

• There are unit/integration tests that verify all acceptance criterias of the issue
• New tests are written to ensure backwards compatibility with further versions
• The behavior is tested manually
• The change has been verified by a QA run
• The impact of the changes is verified by a benchmark

Documentation:

• The documentation is updated (e.g. BPMN reference, configuration, examples, get-started guides, etc.)
• New content is added to the release announcement

[npepinpe]

The analyse-java script failed here since there is no main branch yet 😄

[korthout]

LGTM 🔥 Thanks @npepinpe

[github-actions]

Backport failed for stable/1.2, because it was unable to cherry-pick the commit(s).

Please cherry-pick the changes locally.

git fetch origin stable/1.2
git worktree add -d .worktree/backport-8721-to-stable/1.2 origin/stable/1.2
cd .worktree/backport-8721-to-stable/1.2
git checkout -b backport-8721-to-stable/1.2
ancref=$(git merge-base 52d2be30cdc9245ca15917303e97807b58ed682b b6ed008bb252ccb5a1ec995bf0245bc2a51f7b67)
git cherry-pick -x $ancref..b6ed008bb252ccb5a1ec995bf0245bc2a51f7b67

[github-actions]

Backport failed for stable/1.3, because it was unable to create a new branch.

Please cherry-pick the changes locally.

git fetch origin stable/1.3
git worktree add -d .worktree/backport-8721-to-stable/1.3 origin/stable/1.3
cd .worktree/backport-8721-to-stable/1.3
git checkout -b backport-8721-to-stable/1.3
ancref=$(git merge-base 52d2be30cdc9245ca15917303e97807b58ed682b b6ed008bb252ccb5a1ec995bf0245bc2a51f7b67)
git cherry-pick -x $ancref..b6ed008bb252ccb5a1ec995bf0245bc2a51f7b67