[improvement](external statistics)Fix external stats collection bugs.

[Jibing-Li]

This pr has four changes:

1. Collect external table row count when execute analyze database.
2. Support show cached table stats (row count)
3. Support alter external table column stats.
4. Refresh/Invalidate table row count stat memory cache when analyze task finished and drop table stats.

Proposed changes

Issue Number: close #xxx

Further comments

If this is a relatively large or complex change, kick off the discussion at dev@doris.apache.org by explaining why you chose the solution you did and what alternatives you considered, etc...

[Jibing-Li]

run buildall

[hello-stephen]

(From new machine)TeamCity pipeline, clickbench performance test result:
the sum of best hot time: 47.85 seconds
stream load tsv: 513 seconds loaded 74807831229 Bytes, about 139 MB/s
stream load json: 20 seconds loaded 2358488459 Bytes, about 112 MB/s
stream load orc: 64 seconds loaded 1101869774 Bytes, about 16 MB/s
stream load parquet: 31 seconds loaded 861443392 Bytes, about 26 MB/s
insert into select: 29.2 seconds inserted 10000000 Rows, about 342K ops/s
storage size: 17162290922 Bytes

[morningman]

Please add some regression test

[Jibing-Li]

run buildall

[Jibing-Li]

run buildall

[hello-stephen]

(From new machine)TeamCity pipeline, clickbench performance test result:
the sum of best hot time: 45.81 seconds
stream load tsv: 512 seconds loaded 74807831229 Bytes, about 139 MB/s
stream load json: 20 seconds loaded 2358488459 Bytes, about 112 MB/s
stream load orc: 65 seconds loaded 1101869774 Bytes, about 16 MB/s
stream load parquet: 31 seconds loaded 861443392 Bytes, about 26 MB/s
insert into select: 29.0 seconds inserted 10000000 Rows, about 344K ops/s
storage size: 17162056959 Bytes

[hello-stephen]

(From new machine)TeamCity pipeline, clickbench performance test result:
the sum of best hot time: 45.59 seconds
stream load tsv: 514 seconds loaded 74807831229 Bytes, about 138 MB/s
stream load json: 20 seconds loaded 2358488459 Bytes, about 112 MB/s
stream load orc: 64 seconds loaded 1101869774 Bytes, about 16 MB/s
stream load parquet: 31 seconds loaded 861443392 Bytes, about 26 MB/s
insert into select: 29.1 seconds inserted 10000000 Rows, about 343K ops/s
storage size: 17162503405 Bytes

[github-actions]

PR approved by anyone and no changes requested.

[morningman]

LGTM

[github-actions]

PR approved by at least one committer and no changes requested.