feat: lake: add code quality mode to lake lint

[wkrozowski]

This PR adds a --code-quality option to lake lint that emits builtin linter results as machine-readable JSON entries instead of human-readable diagnostics. Text-linter warnings are aggregated per module and linter into one entry holding the warning count, and environment-linter findings are reported per flagged declaration; both are keyed by the linter's option name. The option implies --builtin-lint and --builtin-only.

[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 17dbc815cf3055e73a9e37d854b8427dc1e9c46c --onto 5b8d06c1764fa367a1e27b3e89f64667eac425af. You can force Mathlib CI using the force-mathlib-ci label. (2026-07-31 15:17:58)
• ❗ Batteries/Mathlib CI will not be attempted unless your PR branches off the nightly-with-mathlib branch. Try git rebase 42a1d764b58761bdda1a175625d4e9dd8e998d9a --onto f2bcf2e8660ab2d16cf3cb50c8e127de0439a337. You can force Mathlib CI using the force-mathlib-ci label. (2026-08-05 11:24:52)

[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 17dbc815cf3055e73a9e37d854b8427dc1e9c46c --onto a39eab69e1eee9ad38f4efe507907b1026a77808. You can force reference manual CI using the force-manual-ci label. (2026-07-31 15:17:59)
• ❗ Reference manual CI will not be attempted unless your PR branches off the nightly-with-manual branch. Try git rebase 42a1d764b58761bdda1a175625d4e9dd8e998d9a --onto 23393b959b33e3a8d15796b2397f8a04c315b9f4. You can force reference manual CI using the force-manual-ci label. (2026-08-05 11:24:53)