Add DateTimeColumn

[Tigrov]

Related PRs

• Use DateTimeColumn db-sqlite#355
• Use DateTimeColumn db-mysql#393
• Use DateTimeColumn db-pgsql#407
• Use DateTimeColumn db-mssql#358
• Use DateTimeColumn db-oracle#323
• Update tests active-record#416

There are several points requiring attention:

1. TIMESTAMP in MySQL и TIMESTAMP WITH LOCAL TIME ZONE in Oracle https://github.com/yiisoft/db/pull/968/files#diff-942d0488fc4c674995e8d5b97876007dda2b9d53eec3b2acc991ab683a3896f3R36-R40
2. Default format of date and time in Oracle https://github.com/yiisoft/db-oracle/pull/323/files#diff-3960e3060b16e67f2ac96cd9c0f69d3884d3361116848080a32dd427e7be44dbR23-R32

Q	A
Is bugfix?	❌
New feature?	✔️
Breaks BC?	✔️
Fixed issues	#725

[codecov]

Codecov Report

Attention: Patch coverage is 93.47826% with 6 lines in your changes missing coverage. Please review.

Project coverage is 99.08%. Comparing base (60c55c4) to head (a59772e).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
src/Schema/Column/DateTimeColumn.php	91.30%	6 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #968      +/-   ##
============================================
- Coverage     99.19%   99.08%   -0.11%     
- Complexity     1611     1630      +19     
============================================
  Files            98       99       +1     
  Lines          3980     4063      +83     
============================================
+ Hits           3948     4026      +78     
- Misses           32       37       +5     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[vjik]

Need to add info to changelog and upgrade.