Improvements to JavaScript analysis

General improvements

Automatic classification of test files has been improved, in particular __tests__ and __mocks__ folders (as used by Jest) are now recognized.
Support for the following frameworks and libraries has been improved:
- cross-spawn
- cross-spawn-async
- exec
- execa
- exec-async
- express
- remote-exec
Support for tracking data flow and taint through getter functions (that is, functions that return a property of one of their arguments) and through the receiver object of method calls has been improved. This may produce more security alerts.
Taint tracking through object property names has been made more precise, resulting in fewer false positive results.
Method calls are now resolved in more cases, due to improved class hierarchy analysis. This may produce more security alerts.

Query	Tags	Purpose
Indirect uncontrolled command line (`js/indirect-command-line-injection`)	correctness, security, external/cwe/cwe-078, external/cwe/cwe-088	Highlights command-line invocations that may indirectly introduce a command-line injection vulnerability elsewhere, indicating a possible violation of CWE-78. Results are not shown on LGTM by default.

Query	Expected impact	Change
Conflicting HTML element attributes (`js/conflicting-html-attribute`)	No changes to results	Results are no longer shown on LGTM by default.
Shift out of range (`js/shift-out-of-range`	Fewer false positive results	This rule now correctly handles BigInt shift operands.
Superfluous trailing arguments (`js/superfluous-trailing-arguments`)	Fewer false-positive results.	This rule no longer flags calls to placeholder functions that trivially throw an exception.
Undocumented parameter (`js/jsdoc/missing-parameter`)	No changes to results	This rule is now run on LGTM, although its results are still not shown by default.

The getName() predicate on functions and classes now gets a name that is inferred from the context if the function or class was not declared with a name.
The two-argument and three-argument variants of DataFlow::Configuration::isBarrier and TaintTracking::Configuration::isSanitizer have been deprecated. Overriding them no longer has any effect. Use isBarrierEdge and isSanitizerEdge instead.