esp32: fix linker script issues

- .text, .text.*, .literal, .literal.* had no matching input section
   rule and were being passed to the output binary verbatim. These
   are all now in the output "text" section as intended.

- various rules in the data section were unnecessarily using KEEP().

- SW_ISR_TABLE wasn't included in linker script anywhere and was
  ending up in its own section, and not the data section as intended.

- noinit section didn't exist at all, now defined.

Issue: ZEP-2508
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>