Simplify tracking main component files

[itaymendel]

Bit needs to define a main file for each component. This file is used as the entry point for the package.json it generates. There are few rules in place to define one of the files as the main file. If all rules fail, Bit prompt an error asking the user to define them with the --main flag.

Seeing that many projects use a convention where all the files of a component are in the same directory, Bit should support it and better detect main files. This is relevant when tracking a directory as a component, or all files in a directory as a single component.

[partent-dir-name].js|ts|tsx|vue

Some teams prefer the main file of a component to be the name of the component, meaning - the same name of the directory that the component is implemented. For example:

$ tree src/components
├── button
│   ├── button.ts
│   ├── button.scss
│   └── button.spec.ts

In this example, for the directory button, the main file is button.ts.

[ranm8]

@davidfirst what is the status of this?

[davidfirst]

@ranm8 , I verified that this was completed. The CHANGELOG file has this:
- [#1714](https://github.com/teambit/bit/issues/1714) auto recognize mainFile when a file added with the same name as its dir