feat(input.tail): Add read_start config for controlling read behavior

[wen-templari]

Summary

Continue #16240

This PR add a read_start config for tail plugin. This option gives user more control over the read behavior.

• It can take following options:

  • save-offset-or-end -- start reading from the persisted offset of the file or, if no offset persisted, start from the end (default)
  • save-offset-or-beginning -- start reading from the persisted offset of the file or, if no offset persisted, start from the beginning
  • end -- start reading from the end of the file ignoring any saved offset
  • beginning -- start reading from the beginning of the file ignoring any saved offset

• Use save-offset-or-end as default because it matches the previous default from_beginning = false behavior.

• After setting read_start, the from_beginning config will be ignored.

• Change store offset logic. Now the plugin will always store offset ignoring the from_beginning config.

Checklist

• No AI generated code was used in this PR

Related issues

resolves #16237

[telegraf-tiger]

Download PR build artifacts for linux_amd64.tar.gz, darwin_arm64.tar.gz, and windows_amd64.zip.
Downloads for additional architectures and packages are available below.

👍 This pull request doesn't change the Telegraf binary size

📦 Click here to get additional PR build artifacts

Artifact URLs

DEB	RPM	TAR GZ	ZIP
amd64.deb	aarch64.rpm	darwin_amd64.tar.gz	windows_amd64.zip
arm64.deb	armel.rpm	darwin_arm64.tar.gz	windows_arm64.zip
armel.deb	armv6hl.rpm	freebsd_amd64.tar.gz	windows_i386.zip
armhf.deb	i386.rpm	freebsd_armv7.tar.gz
i386.deb	ppc64le.rpm	freebsd_i386.tar.gz
mips.deb	riscv64.rpm	linux_amd64.tar.gz
mipsel.deb	s390x.rpm	linux_arm64.tar.gz
ppc64el.deb	x86_64.rpm	linux_armel.tar.gz
riscv64.deb		linux_armhf.tar.gz
s390x.deb		linux_i386.tar.gz
		linux_mips.tar.gz
		linux_mipsel.tar.gz
		linux_ppc64le.tar.gz
		linux_riscv64.tar.gz
		linux_s390x.tar.gz