Added a new sdk method DescribeSystemView and a corresponded Grpc service

[n00bcracker]

Added dedicated method to describe system views via cpp sdk.
Before these changes describing system views was as describing table, but many options and attributes related to ordinal tables were inaccessible for system view, so DescribeTable method was redundant.

[github-actions]

🟢 2025-07-03 16:01:06 UTC The validation of the Pull Request description is successful.

[github-actions]

⚪ 2025-07-04 08:14:36 UTC Pre-commit check linux-x86_64-release-asan for 292cb98 has started.
⚪ 2025-07-04 08:14:48 UTC Artifacts will be uploaded here
⚪ 2025-07-04 08:18:49 UTC ya make is running...
🟡 2025-07-04 10:55:08 UTC Some tests failed, follow the links below. This fail is not in blocking policy yet

Test history | Ya make output | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
16971	16606	0	106	228	31

🟢 2025-07-04 10:56:48 UTC Build successful.
🟡 2025-07-04 10:57:18 UTC ydbd size 3.9 GiB changed* by +1.9 MiB, which is >= 100.0 KiB vs main: Warning

ydbd size dash	main: dc91732	merge: 292cb98	diff	diff %
ydbd size	4 200 266 376 Bytes	4 202 281 680 Bytes	+1.9 MiB	+0.048%
ydbd stripped size	1 455 388 440 Bytes	1 456 126 808 Bytes	+721.1 KiB	+0.051%

^{*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]

⚪ 2025-07-04 08:14:41 UTC Pre-commit check linux-x86_64-relwithdebinfo for 292cb98 has started.
⚪ 2025-07-04 08:14:52 UTC Artifacts will be uploaded here
⚪ 2025-07-04 08:18:48 UTC ya make is running...
🟡 2025-07-04 10:08:10 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?
39426	36669	0	46	2677	34

⚪ 2025-07-04 10:11:34 UTC ya make is running... (failed tests rerun, try 2)
🟢 2025-07-04 10:23:08 UTC Tests successful.

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

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
412 (only retried tests)	383	0	0	2	27

🟢 2025-07-04 10:23:16 UTC Build successful.
🟡 2025-07-04 10:23:35 UTC ydbd size 2.2 GiB changed* by +1012.0 KiB, which is >= 100.0 KiB vs main: Warning

ydbd size dash	main: dc91732	merge: 292cb98	diff	diff %
ydbd size	2 387 749 512 Bytes	2 388 785 808 Bytes	+1012.0 KiB	+0.043%
ydbd stripped size	499 597 864 Bytes	499 752 968 Bytes	+151.5 KiB	+0.031%

^{*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]

⚪ 2025-07-04 21:36:45 UTC Pre-commit check linux-x86_64-relwithdebinfo for acb40db has started.
⚪ 2025-07-04 21:36:56 UTC Artifacts will be uploaded here
⚪ 2025-07-04 21:40:46 UTC ya make is running...
🟡 2025-07-04 23:29:55 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?
39430	36689	0	2	2683	56

⚪ 2025-07-04 23:33:20 UTC ya make is running... (failed tests rerun, try 2)
🟢 2025-07-04 23:41:10 UTC Tests successful.

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

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
794 (only retried tests)	727	0	0	27	40

🟢 2025-07-04 23:41:20 UTC Build successful.
🟡 2025-07-04 23:41:40 UTC ydbd size 2.2 GiB changed* by +996.6 KiB, which is >= 100.0 KiB vs main: Warning

ydbd size dash	main: c59858d	merge: acb40db	diff	diff %
ydbd size	2 387 865 384 Bytes	2 388 885 888 Bytes	+996.6 KiB	+0.043%
ydbd stripped size	499 603 048 Bytes	499 752 104 Bytes	+145.6 KiB	+0.030%

^{*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]

⚪ 2025-07-04 21:36:50 UTC Pre-commit check linux-x86_64-release-asan for acb40db has started.
⚪ 2025-07-04 21:37:01 UTC Artifacts will be uploaded here
⚪ 2025-07-04 21:40:57 UTC ya make is running...
🟡 2025-07-05 00:16:01 UTC Some tests failed, follow the links below. This fail is not in blocking policy yet

Test history | Ya make output | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
16973	16566	0	141	235	31

🟢 2025-07-05 00:17:25 UTC Build successful.
🟡 2025-07-05 00:17:56 UTC ydbd size 3.9 GiB changed* by +1.9 MiB, which is >= 100.0 KiB vs main: Warning

ydbd size dash	main: c59858d	merge: acb40db	diff	diff %
ydbd size	4 200 002 176 Bytes	4 201 989 496 Bytes	+1.9 MiB	+0.047%
ydbd stripped size	1 455 233 272 Bytes	1 455 960 792 Bytes	+710.5 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}