Virtual address space specification, assignment, and booting.

[gparmer]

Summary of this Pull Request (PR)

Adds support for virtual address space knowledge and management into the composer, and feeds that into the booter through the initargs.

• Adds a specification for address spaces including a hierarchy
• Adds intelligence into the composer to assign virtual address names to components that share (or split from) a VAS.
• Adds an initargs description of the address spaces, and integrates them into llbooter.

I'm hoping that this can get rid of the llbooter_vas.c stuff, so I didn't modify that code.

To review, it might be easiest to go through the commits as they are structured in a sequence of successive functionality.

Steps:

1. Parsing and validation of composition scripts. 6340d95237bab5077b19ad47d8b9a83647c08bec (and commits leading up to it)
2. Add an AS representation to the pass structure of the composer for later pass access. 187b371c9b00c0d9d0dbc422c4139682566fd228
3. Order ASes by the parent relationship. ff5cd1c80017e903507a4d6cb6eee734d01bb498
4. Assign virtual addresses based on ASes and the parent relation. 8d11d13f9581ff6deb61657febfe442de3d58a44
5. Synthesize the initargs based on the ASes and addresses. fe7001a993b0084be03dbf8b0ff7176f410ce973
6. Use the initargs and the AS specification in the booter. 8a77c31253b8a934e16eb0d9a2b917fc081e4d96

Intent for your PR

Choose one (Mandatory):

• [ ] This PR is for a code-review and is intended to get feedback, but not to be pulled yet.
• [x] This PR is mature, and ready to be integrated into the repo.

Reviewers (Mandatory):

@evanstella @WenyuanShao @betahxy

Code Quality

As part of this pull request, I've considered the following:

Style:

• [x] Comments adhere to the Style Guide (SG)
• [x] Spacing adhere's to the SG
• [x] Naming adhere's to the SG
• [x] All other aspects of the SG are adhered to, or exceptions are justified in this pull request
• [ ] I have run the auto formatter on my code before submitting this PR (see doc/auto_formatter.md for instructions)

Code Craftsmanship:

• [x] I've made an attempt to remove all redundant code
• [x] I've considered ways in which my changes might impact existing code, and cleaned it up
• [x] I've formatted the code in an effort to make it easier to read (proper error handling, function use, etc...)
• [x] I've commented appropriately where code is tricky
• [x] I agree that there is no "throw-away" code, and that code in this PR is of high quality

Testing

Some coverage of the tests.

[betahxy]

Excellent PR! Thanks for the detailed review steps here.