TA and endpoint integration

• rename ta-endpoint as endpoint
• Add description about endpoint in README

Files will be changed:

• .gitignore

  • integrate with tangle-accelerator

• .gitsubmodule

  • integrate with tangle-accelerator

• main.c

  • rename to endpoint.c

• /hooks

  • remove hooks under endpoint

• .clang-format

  • remove the one under endpoint

• issue

  • Move directly after examining the status of each issue

• PR

  • merge: feat: Unify low-level operation with consistent HAL interface

• defined_error.h

  • error and status and return status should be merge into status_t

• move HAL.md to doc directory

• connectivity integrate into TA connectivity

  • change http to https

• tests migrate into endpoint

• migrate utils/connectivity into tangle-accelerator

• remove README.md inside endpoint

• 要能夠在TOPLEVEL就能build to endpoint target(simulator 或是 wp7702)

  • Add to TA Makefile
  • make TARGET=wp7702 endpoint
  • make TARGET=sim endpoint

• 利用bazel建立cross compile規則(能夠混用toolchain)

• Makefile(modify):

  • Makefile under tangle-accelerator should be modified
  • third_party LDFLAGS, lib link flags
  • INCLUDES directory path

• defined_error.h:

  • Remove defined_error.h in ta-endpoint, and use ta_error.h to replace it.

• unit test:

• conn_http should have unit test.
• https should have unit test.
• trytes should have unit test.
• endpoint should have unit test.