Rewrite exports parser

[huozhi]

This PR changes the way of how bunchee parsing package exports and matching with entries.

While making the lint feature, I realize we could collect the source files first instead of do a matching for possible entry file when we create a job each time.

The approach now is to have a export path to output files and conditions mapping

'.' -> [
   ['./dist/index.js', 'require'],
   ['./dist/index.mjs', 'import'],
]

If you have more special conditions, the export type will become a composed type connected by '.'

'.' -> [
   ['./dist/index.js', 'require'],
   ['./dist/index.mjs', 'import'],
   ['./dist/index.react-server.mjs', 'import.react-server'],
]

Then we'll collect all the entry files, including executable binaries, they'll be

'./index' -> {
   'import': '<>/src/index.mjs',
   'default': '<>/src/index.js',
},
'./index.development' -> {
   'development': <>/src/index.js,
},

As you can see, the entry ./index will have 2 outputs: one is ESM format (import), another is default format, the default is based evaluated based on the package type.

We'll normalize the keys of the collected entries key, and do a overlapping with the collected output files. So that each entry file with its corresponding output files can become the building jobs later.

Previous approah of parsing export paths is too complex especially composing with development and production conditions.

Fixes #469
Fixes #407