feat: Create Chat State Manager

Closes #1678

See merge request gitlab-org/gitlab-vscode-extension!2274



Merged-by: Michael Angelo Rivera <arivera@gitlab.com>
Approved-by: Elwyn Benson <ebenson@gitlab.com>
Approved-by: Michael Angelo Rivera <arivera@gitlab.com>
Reviewed-by: Olena Horal-Koretska <ohoralkoretska@gitlab.com>
Co-authored-by: Olena Horal-Koretska <ohoralkoretska@gitlab.com>

chore(deps): update dependency @gitlab-org/gitlab-lsp to ^7.5.0

See merge request gitlab-org/gitlab-vscode-extension!2281



Merged-by: Michael Angelo Rivera <arivera@gitlab.com>
Approved-by: Michael Angelo Rivera <arivera@gitlab.com>
Co-authored-by: GitLab Renovate Bot <gitlab-bot@gitlab.com>