feat: split screen Terminal

[starpit]

Fixes #4814

Description of what you did:

My PR is a:

• 💥 Breaking change
• 🐛 Bug fix
• 💅 Enhancement
• 🚀 New feature

Please confirm that your PR fulfills these requirements

• Multiple commits are squashed into one commit.
• The commit message follows Conventional Commits, which allows us to autogenerate release notes; e.g. fix(plugins/plugin-k8s): fixed annoying bugs
• All npm dependencies are pinned.

[codecov]

Codecov Report

Merging #4815 into master will increase coverage by 0.07%.
The diff coverage is 75.94%.

@@            Coverage Diff             @@
##           master    #4815      +/-   ##
==========================================
+ Coverage   59.59%   59.66%   +0.07%     
==========================================
  Files          77       77              
  Lines        2408     2452      +44     
  Branches      588      604      +16     
==========================================
+ Hits         1435     1463      +28     
- Misses        746      759      +13     
- Partials      227      230       +3     

Impacted Files	Coverage Δ
packages/core/src/index.ts	100.00% <ø> (ø)
packages/core/src/models/NavResponse.ts	100.00% <ø> (ø)
packages/core/src/models/execOptions.ts	60.00% <ø> (ø)
packages/core/src/models/mmr/types.ts	100.00% <ø> (ø)
packages/core/src/webapp/queueing.ts	70.00% <ø> (-1.43%)	⬇️
packages/core/src/core/events.ts	75.36% <70.68%> (-17.98%)	⬇️
packages/core/src/webapp/tab.ts	71.42% <77.77%> (+4.76%)	⬆️
packages/core/src/repl/exec.ts	74.30% <100.00%> (-1.09%)	⬇️
packages/core/src/webapp/cancel.ts	100.00% <100.00%> (ø)

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