[clang-apply-replacements] Added an option to ignore insert conflict.

If two different texts are inserted at the same offset, clang-apply-replacements prints the conflict error and discards all fixes. This patch adds support for adjusting conflict offset and keeps running to continually fix them.

https://godbolt.org/z/P938EGoxj doesn't have any fixes when I run run-clang-tidy.py to generate a YAML file with clang-tidy and fix them with clang-apply-replacements. The YAML file has two different header texts insertions at the same offset, unlike clang-tidy with '-fix', clang-apply-replacements does not adjust for this conflict.

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D123924