[api-extractor]: --typescript-compiler-folder is not properly handled within Extractor._checkCompilerCompatibility() call

[Hotell]

Run:
api-extractor run --local --typescript-compiler-folder ./node_modules/typescript --verbose

Summary

When --typescript-compiler-folder flag is used api-extractor prints miss-leading warning.

Analysis will use the bundled TypeScript version 4.1.5
...
...
*** The target project appears to use TypeScript 4.2.3 which is newer than the bundled compiler engine; consider upgrading API Extractor. ...

1. https://github.com/microsoft/rushstack/blob/master/apps/api-extractor/src/cli/RunAction.ts#L141

• typescriptCompilerFolder value is properly set: /<PATH>/node_modules/typescript

2. https://github.com/microsoft/rushstack/blob/master/apps/api-extractor/src/api/CompilerState.ts#L140-L144

• program is properly created with user provided tsc binary.

3. https://github.com/microsoft/rushstack/blob/master/apps/api-extractor/src/api/Extractor.ts#L211

• _checkCompilerCompatibility() is being called without proper tsc path that is being used

4. miss-leading warning are printed out to user

Repro steps

Expected result:
Provide correct info to user that his specified version of TSC is used

Actual result:
Miss leading warnings what TSC is being used

Details

Standard questions

Please answer these questions to help us investigate your issue more quickly:

Question	Answer
@microsoft/api-extractor version?	7.13.2
Operating system?	Mac
API Extractor scenario?	rollups (.d.ts)
Would you consider contributing a PR?	Maybe
TypeScript compiler version?	4.2.3
Node.js version (node -v)?	15

[DLehenbauer]

@hottell - I think the warning is correct. Per docs, api-extractor always uses the bundled compiler. The `--typescript-compiler-folder' option allows you to substitute system typings from your project's toolchain.

See compiler version incompatibilities on this page:
https://api-extractor.com/pages/setup/invoking/

It's also there in the last sentence of the usage, but you have to read carefully:

  --typescript-compiler-folder PATH
                        API Extractor uses its own TypeScript compiler engine 
                        to analyze your project. If your project is built 
                        with a significantly different TypeScript version, 
                        sometimes API Extractor may report compilation errors 
                        due to differences in the system typings (e.g. lib.
                        dom.d.ts). You can use the 
                        "--typescriptCompilerFolder" option to specify the 
                        folder path where you installed the TypeScript 
                        package, and API Extractor's compiler will use those 
                        system typings instead.