feat: add FM project

[jybai]

Issue #, if available:

Description of changes:

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[OctoberChang]

@jybai , thanks for creating the pull request.

Here are some suggestions before merge:

• We need to pin down the dependencies (e.g., libpecos version), as your code depends on the c/c++ libraries in pecos folder.
• We can not include binary pdf files (i.e., FM_O_dk.pdf). You can write math equations in Github readme markdown, or attach a hyper-link to the pdf stored on other cloud storages.

Let me know if you have time to address it. Otherwise, I will close this pull request.

[jybai]

@OctoberChang Thank you for your prompt reply. I think I'd be able to fix it. The pdf part is simple. Regarding the dependency, I'm not sure what exactly should I do. Should I specify which version of pecos is used in the README?

[OctoberChang]

@OctoberChang Thank you for your prompt reply. I think I'd be able to fix it. The pdf part is simple. Regarding the dependency, I'm not sure what exactly should I do. Should I specify which version of pecos is used in the README?

1. Here are an example you can put into Install Section of the README.md.

# git clone with a specific release tag v0.4.0
git clone -b v0.4.0 https://github.com/amzn/pecos.git;
cd pecos/example/fm;
make all

2. Another suggestion is the folder name fm could be a bit ambiguous. Can you rename it to more specific one, such as fm-for-xmc ?

[jybai]

@OctoberChang I have updated the directory name, README, and FM complexity doc file according to suggestions. Please let me know if anything else needs fixing. Many thanks.