Foreign Key Check logic causes conflicts on sqlite db implementation.

[georgestephanis]

I was testing this on Studio as a local dev environment (which implements sqlite db instead of MySQL / MariaDB) and got some issues due to assumptions in the code about foreign key checks --

https://github.com/stellarwp/schema/blob/main/src/Schema/Tables/Contracts/Table.php#L274-L284

<b>Warning</b>:  Attempt to read property "Value" on null in <b>/wordpress/wp-content/plugins/kadence-blocks/vendor/vendor-prefixed/stellarwp/schema/src/Schema/Tables/Contracts/Table.php</b> on line <b>179</b><br />
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<b>Warning</b>:  Attempt to read property "Value" on null in <b>/wordpress/wp-content/plugins/kadence-blocks/vendor/vendor-prefixed/stellarwp/schema/src/Schema/Tables/Contracts/Table.php</b> on line <b>184</b><br />
<br />
<b>Warning</b>:  Attempt to read property "Value" on null in <b>/wordpress/wp-content/plugins/kadence-blocks/vendor/vendor-prefixed/stellarwp/schema/src/Schema/Tables/Contracts/Table.php</b> on line <b>179</b><br />
<br />
<b>Warning</b>:  Attempt to read property "Value" on null in <b>/wordpress/wp-content/plugins/kadence-blocks/vendor/vendor-prefixed/stellarwp/schema/src/Schema/Tables/Contracts/Table.php</b> on line <b>184</b><br />

It feels like some safety rails around key_check testing if it's available would be useful for implementation in various environments.