External data sources: describe in SDK

[jepett0]

DescribeExternalDataSource and DescribeExternalTable methods in SDK.

Changelog entry

Changelog category

• Not for changelog (changelog entry is not required)

Additional information

• external data sources: describe #14436

[dorooleg]

lgtm

[github-actions]

⚪ 2025-02-12 19:32:26 UTC Pre-commit check linux-x86_64-release-asan for 5d5baf4 has started.
⚪ 2025-02-12 19:32:38 UTC Artifacts will be uploaded here
⚪ 2025-02-12 19:35:45 UTC ya make is running...
🟡 2025-02-12 20:42:15 UTC Some tests failed, follow the links below. This fail is not in blocking policy yet Going to retry failed tests...

Test history | Ya make output | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
13542	13464	0	24	21	33

⚪ 2025-02-12 20:43:26 UTC ya make is running... (failed tests rerun, try 2)
🟡 2025-02-12 20:55:22 UTC Some tests failed, follow the links below. This fail is not in blocking policy yet Going to retry failed tests...

Test history | Ya make output | Test bloat | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
122 (only retried tests)	82	0	4	6	30

⚪ 2025-02-12 20:55:30 UTC ya make is running... (failed tests rerun, try 3)
🟡 2025-02-12 21:07:15 UTC Some tests failed, follow the links below. This fail is not in blocking policy yet

Test history | Ya make output | Test bloat | Test bloat | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
71 (only retried tests)	33	0	4	4	30

🟢 2025-02-12 21:07:23 UTC Build successful.
🟡 2025-02-12 21:07:52 UTC ydbd size 3.6 GiB changed* by +1.6 MiB, which is >= 100.0 KiB vs main: Warning

ydbd size dash	main: 74671b6	merge: 5d5baf4	diff	diff %
ydbd size	3 876 525 608 Bytes	3 878 215 360 Bytes	+1.6 MiB	+0.044%
ydbd stripped size	1 357 556 192 Bytes	1 358 239 360 Bytes	+667.2 KiB	+0.050%

^{*please be aware that the difference is based on comparing your commit and the last completed build from the post-commit, check comparation}

[github-actions]

⚪ 2025-02-12 19:32:59 UTC Pre-commit check linux-x86_64-relwithdebinfo for 5d5baf4 has started.
⚪ 2025-02-12 19:33:12 UTC Artifacts will be uploaded here
⚪ 2025-02-12 19:36:05 UTC ya make is running...
🟡 2025-02-12 20:40:09 UTC Some tests failed, follow the links below. Going to retry failed tests...

Test history | Ya make output | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
27710	25118	0	2	2456	134

⚪ 2025-02-12 20:42:31 UTC ya make is running... (failed tests rerun, try 2)
🟢 2025-02-12 20:54:45 UTC Tests successful.

Test history | Ya make output | Test bloat | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
208 (only retried tests)	81	0	0	0	127

🟢 2025-02-12 20:54:52 UTC Build successful.
🟡 2025-02-12 20:55:12 UTC ydbd size 2.1 GiB changed* by +684.1 KiB, which is >= 100.0 KiB vs main: Warning

ydbd size dash	main: 4045ae8	merge: 5d5baf4	diff	diff %
ydbd size	2 229 249 320 Bytes	2 229 949 856 Bytes	+684.1 KiB	+0.031%
ydbd stripped size	473 342 904 Bytes	473 416 824 Bytes	+72.2 KiB	+0.016%

^{*please be aware that the difference is based on comparing your commit and the last completed build from the post-commit, check comparation}

[CyberROFL]

lgtm