Added connection string to clickhouse-client

[Demilivor]

Closes #29880

Connection string syntax:

clickhouse://[user_info@][hosts_and_ports][/dbname][?query_parameters]

The connection string must be passed as first argument to clickhouse-client. It can be combined with arbitrary other command line options except --host(h) and --port.

Examples

clickhouse-client "clickhouse://localhost:9000/my_database" --query "SELECT 1"
clickhouse-client "clickhouse://localhost:9000" --user default
clickhouse-client "clickhouse://some_user%40some_mail.com:secret@localhost:9000" # %40 encodes @

**Known issues**
Currently, a password in the connection string and an empty password passed via `--password` makes the client ignore the password:

``` bash
clickhouse-client "clickhouse://user_with_password:secret@/" --password

# clickhouse response:
ClickHouse client version 23.5.1.1.
Password for user (user_with_password): 

Error has the same root cause as: #50459. Internally, the connection string is converted to command line options.

Changelog category (leave one):

• New Feature

Changelog entry (a user-readable short description of the changes that goes to CHANGELOG.md):

clickhouse-client can now be called with a connection instead of "--host", "--port", "--user" etc.

[Demilivor]

Good day @rschu1ze please be reviewer of this pull request and add a label 'can be tested'.

[robot-ch-test-poll]

This is an automated comment for commit 4db8fa3 with description of existing statuses. It's updated for the latest CI running
The full report is available here
The overall status of the commit is 🔴 failure

Check name	Description	Status
AST fuzzer	Runs randomly generated queries to catch program errors. The build type is optionally given in parenthesis. If it fails, ask a maintainer for help	🟢 success
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Stateful tests	Runs stateful functional tests for ClickHouse binaries built in various configurations -- release, debug, with sanitizers, etc	🟢 success
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[rschu1ze]

Haven't looked at the C++ uri parsing code and the test yet but my first impression is positive. Thanks!

[Demilivor]

I didn't have time to finish the changes today. I plan to finish and update on Tuesday.

I'm still not sure about the renaming:

user_info->userspec
hosts_and_ports->hostspec
 query_parameters->paramspec

Also not sure about disabling --user(-u), --password and --database(d) along with the connection string

I'm planning a couple more changes:
Prohibit the use of --connection client option along with connection string.
If user_info is username:@. It has ':' but the password is empty, then client will ask the user for the password in the same way:
clickhouse-client --user username --password

[rschu1ze]

The remaining comments are minor and of cosmetic nature. Besides them, everything looks good, thanks!

[rschu1ze]

Interesting. Didn't know that clickhouse-client had such a shortcut.

[Demilivor]

Small inline question about constants:
Should we add public constant constexpr std::string_view ASK_USER_PASSWORD = "\n"sv somewhere in ClientBase.h?
Using "\n" as a special case for password requires adding comments in several parts of code, it is not oblivious for other non-familiar developers with code base what does "\n" means without comments.
ASK_USER_PASSWORD.

[rschu1ze]

Yes, that would be a good idea. But it is not urgent, totally fine to do this in some follow-up PR (e.g. here: #50966)