Refactor TSCH_EXEC and SMBEXEC

[azoxlpf]

Description

Following #1191, this PR cleans up TSCH_EXEC and SMBEXEC by removing duplicate authentication parameters (username, password, hashes, share_name, etc.) and the legacy manual RPC transport setup, since NXCRPCConnection now handles credentials via the SMB connection object. Call sites in smb.py and schtask_as.py are updated accordingly, and unused execute_fileless code is removed from SMBEXEC

Type of change

Insert an "x" inside the brackets for relevant items (do not delete options)

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Deprecation of feature or functionality
• This change requires a documentation update
• This requires a third party update (such as Impacket, Dploot, lsassy, etc)
• This PR was created with the assistance of AI (list what type of assistance, tool(s)/model(s) in the description)

Setup guide for the review

• nxc smb <IP> -u <user> -p '<pass>' --exec-method smbexec -x whoami

• nxc smb <IP> -u <user> -p '<pass>' --exec-method smbexec -x whoami --no-output

• nxc smb <IP> -u <user> -p '<pass>' --exec-method smbexec -X "Get-Date; hostname"

• nxc smb <IP> -u <user> -p '<pass>' --exec-method atexec -x whoami

• nxc smb <IP> -u <user> -p '<pass>' --exec-method atexec -x whoami --no-output

• nxc smb <IP> -u <user> -p '<pass>' --exec-method atexec -X "hostname; whoami"

• nxc smb <IP> -u <user> -p '<pass>' -M schtask_as -o USER=Administrator CMD=whoami

• nxc smb <IP> -u <user> -p '<pass>' -M schtask_as -o USER=Administrator CMD=whoami SILENTCOMMAND=True

Screenshots (if appropriate):

I ran several tests, and it sounds good to me :

Checklist:

Insert an "x" inside the brackets for completed and relevant items (do not delete options)

• I have ran Ruff against my changes (poetry: poetry run ruff check ., use --fix to automatically fix what it can)
• I have added or updated the tests/e2e_commands.txt file if necessary (new modules or features are required to be added to the e2e tests)
• If reliant on changes of third party dependencies, such as Impacket, dploot, lsassy, etc, I have linked the relevant PRs in those projects
• I have linked relevant sources that describes the added technique (blog posts, documentation, etc)
• I have performed a self-review of my own code (not an AI review)
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (PR here: https://github.com/Pennyw0rth/NetExec-Wiki)

[NeffIsBack]

As always thanks for the work! All looking much cleaner now, LGTM: