feat: introduce TCP.SSL

[algebraic-dev]

This PR adds SSL sockets and handling of Sessions and Contexts

[mathlib-lean-pr-testing]

Mathlib CI status (docs):

• ❗ Batteries/Mathlib CI will not be attempted unless your PR branches off the nightly-with-mathlib branch. Try git rebase 86175bea00f2d963a8c1367ac8ae67dd70ab32ea --onto e6df474dd9c3ad0e21771eaa808c53f66222216d. You can force Mathlib CI using the force-mathlib-ci label. (2026-03-24 19:22:31)
• ❗ Batteries/Mathlib CI will not be attempted unless your PR branches off the nightly-with-mathlib branch. Try git rebase 337f1c455b3355fb9c4d50e55ab7ee4a875af6a1 --onto 4786e082dca22873d14d2a5b9b7c8843380c6e78. You can force Mathlib CI using the force-mathlib-ci label. (2026-03-28 17:10:33)

[leanprover-bot]

Reference manual CI status:

• ❗ Reference manual CI will not be attempted unless your PR branches off the nightly-with-manual branch. Try git rebase 86175bea00f2d963a8c1367ac8ae67dd70ab32ea --onto cfa8c5a036d6990635c6ec50b02d0e806995cec3. You can force reference manual CI using the force-manual-ci label. (2026-03-24 19:22:33)
• ❗ Reference manual CI will not be attempted unless your PR branches off the nightly-with-manual branch. Try git rebase 337f1c455b3355fb9c4d50e55ab7ee4a875af6a1 --onto cfa8c5a036d6990635c6ec50b02d0e806995cec3. You can force reference manual CI using the force-manual-ci label. (2026-03-28 17:10:34)