Closes #7248 Preconnect to external domains - Data insertion part

[Khadreal]

Description

Add database structure for preconnect external domains

Fixes #7248

Type of change

• New feature (non-breaking change which adds functionality).

Detailed scenario

N/A

Technical description

Documentation

Add database queries, schema, ajax controller for preconnect external domains features.

Mandatory Checklist

Code validation

• I validated all the Acceptance Criteria. If possible, provide screenshots or videos.
• I triggered all changed lines of code at least once without new errors/warnings/notices.
• I implemented built-in tests to cover the new/changed code.

Code style

• I wrote a self-explanatory code about what it does.
• I protected entry points against unexpected inputs.
• I did not introduce unnecessary complexity.
• Output messages (errors, notices, logs) are explicit enough for users to understand the issue and are actionnable.

[codacy-production]

Coverage summary from Codacy

See diff coverage on Codacy

Coverage variation	Diff coverage
Report missing for fc03b071	✅ 52.94% (target: 50.00%)

Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (fc03b07)	Report Missing	Report Missing	Report Missing
Head commit (fb9dbf1)	39349	17162	43.61%

Coverage variation is the difference between the coverage for the head and common ancestor commits of the pull request branch: <coverage of head commit> - <coverage of common ancestor commit>

Diff coverage details

	Coverable lines	Covered lines	Diff coverage
Pull request (#7310)	102	54	52.94%

Diff coverage is the percentage of lines that are covered by tests out of the coverable lines that the pull request added or modified: <covered lines added or modified>/<coverable lines added or modified> * 100%

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Footnotes

1. Codacy didn't receive coverage data for the commit, or there was an error processing the received data. Check your integration for errors and validate that your coverage setup is correct. ↩

[MathieuLamiot]

@Khadreal the CI is failing
If this needs another PR to fix the test, please write it down here so we can know what needs to be done.

[wordpressfan]

table is created successfully, good job @Khadreal