chore: replace formatter with spotless [skip ci]

[sissbruecker]

Replaces the formatter-maven-plugin with spotless.

This uses a minimal configuration for now that results in minimal formatting changes, which allows cherry-picking to version branches. A follow-up PR could enable further features and reformat the code on main.

[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[vaadin-bot]

Hi @sissbruecker and @ZheSun88, when i performed cherry-pick to this commit to 24.4, i have encountered the following issue. Can you take a look and pick it manually?
Error Message:
Error: Command failed: git cherry-pick aa143ec
error: could not apply aa143ec... chore: replace formatter with spotless [skip ci] (#6512)
hint: After resolving the conflicts, mark them with
hint: "git add/rm ", then run
hint: "git cherry-pick --continue".
hint: You can instead skip this commit with "git cherry-pick --skip".
hint: To abort and get back to the state before "git cherry-pick",
hint: run "git cherry-pick --abort".

[vaadin-bot]

Hi @sissbruecker and @ZheSun88, when i performed cherry-pick to this commit to 23.5, i have encountered the following issue. Can you take a look and pick it manually?
Error Message:
Error: Command failed: git cherry-pick aa143ec
error: could not apply aa143ec... chore: replace formatter with spotless [skip ci] (#6512)
hint: After resolving the conflicts, mark them with
hint: "git add/rm ", then run
hint: "git cherry-pick --continue".
hint: You can instead skip this commit with "git cherry-pick --skip".
hint: To abort and get back to the state before "git cherry-pick",
hint: run "git cherry-pick --abort".

[vaadin-bot]

Hi @sissbruecker and @ZheSun88, when i performed cherry-pick to this commit to 24.3, i have encountered the following issue. Can you take a look and pick it manually?
Error Message:
Error: Command failed: git cherry-pick aa143ec
error: could not apply aa143ec... chore: replace formatter with spotless [skip ci] (#6512)
hint: After resolving the conflicts, mark them with
hint: "git add/rm ", then run
hint: "git cherry-pick --continue".
hint: You can instead skip this commit with "git cherry-pick --skip".
hint: To abort and get back to the state before "git cherry-pick",
hint: run "git cherry-pick --abort".

[vaadin-bot]

Hi @sissbruecker and @ZheSun88, when i performed cherry-pick to this commit to 23.4, i have encountered the following issue. Can you take a look and pick it manually?
Error Message:
Error: Command failed: git cherry-pick aa143ec
error: could not apply aa143ec... chore: replace formatter with spotless [skip ci] (#6512)
hint: After resolving the conflicts, mark them with
hint: "git add/rm ", then run
hint: "git cherry-pick --continue".
hint: You can instead skip this commit with "git cherry-pick --skip".
hint: To abort and get back to the state before "git cherry-pick",
hint: run "git cherry-pick --abort".